Here we report that a two-phase reaction of methane/dioxygen (CH4/O2) with trifluoroacetic acid (HTFA, CF3CO2H) affords methyl trifluoroacetate (MTFA, CH3OCOCF3) in high yield under visible-light at 298 K (25 o C), which breaks through the selectivity-conversion limit of the aerobic oxidation of methane successfully. Furthermore, MTFA is also hydrolyzed to give methanol (CH3OH) easily at room temperature to complete the two-step conversion of methane to methanol under ambient conditions (Scheme 1b). In the aerobic oxidations, sodium nitrite (NaNO2) is just employed in a catalytic amount in aqueous HCl/HTFA solution without any metal complexes or special additives. In a batch reaction of CH4/O2 (1:5, 35 mL, 0.4 MPa) with 2.4 mol% NaNO2 based on methane, MTFA was obtained in 91.3% yield with the methane conversion up to 100% in 3 days. On the other hand, to keep the constant pressure of gases in the reactor, CH4/O2 (2:1, 35 mL, 0.1 MPa) was used as a buffer gas with 2.3 μmol NaNO2 during a continuous experiment. The external CH4/O2 (2:1, 42 mL, 0.1 MPa) was inputted within 7 days. MTFA was produced in 88.6% yield (96% selectivity), and the methane conversion was 92% based on the external CH4/O2 under ambient conditions in this reaction (Scheme 1c). The turnover frequency (TOF) was 2.5 mol MTFA mol NaNO 2 -1 h -1 , and the turnover number (TON) was over 400.