Dense wavelength division multiplexing (DWDM) SDH rings have been extensively deployed in core networks and metropolitan area networks (MAN). Furthermore, advances in optical ADM (OADM), optical DXC (OXC) and Erbium-doped fiber amplifiers (EDFA) have resulted in evolving core networks and MAN to all-optical networks. Due to its low cost, flexibility and low loss, OADM based on fiber grating and optical circulator has exhibited potential in applying to DWDM SDH ring networks[l]. Although fiber-grating based OADM has the feature of low loss, EDFA is always deployed to compensate the loss and further improve the network performances. However, amplified spontaneous emission (ASE) noise will limit the improvement of the network performances[2]. Fiber grating is a stable and reliable filter, and this high performance filter is ideal for simultaneously achieving wide-band signal transmission and a high-level of ASE noise suppression in amplified DWDM networks. In this article, performance analysis of amplified DWDM SDH ring with OADM based on fiber grating and optical circulator has been performed with an explicit method -Signal Flow Graph. The results show that the throughput and the power penalty of amplified DWDM SDH ring with fiber-grating based OADM are effectively improved, considering ASE suppression by fiber gratings. Additionally, the network performances of pre-amplifying, post-amplifying and in-line amplifying schemes are analyzed, implying that the network performance optimization of amplified DWDM SDH ring with fiber-grating based OADM could be achieved with proper scheme.