One of the other traditional synthetic ways for preparing aromatic amines uses inexpensive and readily available nitroarenes for reductive amination . In these cases, with methanol as an economical and sustainable C1 source in the reaction for methylation and water as the sole byproduct, this method is more attractive and promising from both economic and environmental perspectives . Moreover, the dehydrogenation performance of methanol is much higher than that of higher alcohols such as ethanol and isopropanol. Therefore, it is of great practical importance to use a tandem and cost-effective one-pot method to selectively synthesize Nmethylated amines using nitroarenes as the feedstock methanol as the methylation and hydrogenation source. The synthesis of N-methylated amines by such methods is less common although there have been a few reports in recent years (Scheme 1). First, the ruthenium NNN pincer complexes, which can efficiently catalyze the N-methylation of nitroarenes as well as vinyl nitro compounds into mono-and dimethylated amines, and the corresponding mechanisms pathways have been proposed . Recent reports have also applied this tandem transformation system based on Ir, Ru, Pd, Mn, Pt. Among them, Ir is mainly based on functional NHC ligands. which confer Ir higher activity and selectivity, which improves the substrate application range of the series conversion system, in which N-heterocyclic carbene-iridium (NHC-Ir) coordination assemblies based on bis-pyrenoimidazolium salts are heterogeneous catalyst and has reusability . The Ru catalyst system uses commercial precursor [RuCl2(p-cymene)2]2 and NNN pincer (aminepyridine-imine, API) as ligand to prepare the efficient catalyst in-situ . The Pd based catalysts, which are generally referred to as a catalyst system composed of commercial catalyst Pd/C or Pd (OAc)2 and ligand 1-[2-isopropyl (isopropyl) phenyl]-2-[tert-butyl (2-pyridinyl) phosphino]-1Himidazole, usually require high catalyst loading, excessive auxiliary ligands, and longer reaction time . It has been reported that the synthesis catalyst [(N,N′-bis(diisopropylphosphino)-2,6diaminopyridine)Mn(CO)3][Br] can obtain 90% separation yields after optimization, but the existence of alkali and molecular sieve with a high chemical equivalence ratio is necessary . The previously reported Pt/C also gave high yields for this reaction, but it also required higher reaction temperatures and reaction times . In summary, to make this series conversion reaction more widely used, the reaction conditions were milder and more sustainable, therefore, the heterogeneous catalysis of different metals was applied to the N-monomethylation of nitroaromatic hydrocarbons with methanol as methylation and hydrogenation source. Scheme 1. Synthesis of N-methylamines by using methanol. Covalent organic frame materials are a kind of periodic and crystalline organic porous polymers connected by covalent bonds. Because of its good thermal and chemical stability, ordered pore structure, good crystallinity, and designability of the unit structure, it has become a research hotspot in recent years. Among them, the Schiff base COFs are connected by C=N, and both N in the precursor and N in the Schiff base can be used to anchor metal atoms to form strong coordination bonds. Nowadays, COFs are used in Suzuki reaction , Sonogashira reaction , Diels Alder reaction , Michael addition reaction , and so on , but there are few reports on the application of COFs supported transition metal in N-methylation reaction. Specifically, when concerning the challenging tandem hydrogenation and N-mono-methylation of nitroaromatic hydrocarbons, especially when methanol served as both methylation and hydrogenation source, it undoubtedly requires that the transition metals should have the unique properties which can dehydrogenate methanol for reductive amination and further catalyze the Nmethylation of amines selectively, and the precious metals are normally one of the choices. As mentioned above, catalyst stability and recyclability are of great importance facing the current environmental and economical issues. So, in combination with the advantages of both COF materials and precious transition metal, developing high and efficient heterogeneous catalysts can not only facilitate the challenging tandem experimental operation but also can recover the catalyst, this definitely will open COF supported transition metal catalyst wide application in both academic and industrial. Therefore, we designed and synthesized two kinds of Rh-anchored COFs using melamine as the precursor, and reported for the first time the tandem reaction of transfer hydrogenation and N-mono-methylation of nitroaromatic hydrocarbons with methanol as the methylation source. In addition, the catalyst is suitable for nitroaromatic hydrocarbons with various reaction functional groups and can be recycled without losing reactivity.