Abstract: The eastern power grid is an important power source base in Heilongjiang Province, with abundant solar, wind and pumped storage resources. The rich power is mainly sent to the Heilongjiang central power grid and the Jilin power grid for consumption. However, the transmission capacity is limited by the temporarily stable of the 500 kV Linping line and the carrying capacity of the 220 kV Fangde A＆B single circuit line. With the sharp increase in the installed capacity of the eastern power grid, it is necessary to study the limit transmission power of the transmission section in the region, thereby improving the power transmission capacity in the region. Using the power system analysis software package（PSASP） as the calculation platform, the power flow calculation and transient stability calculation are used to analyze the stable limit transmission power of the eastern power grid under various operating modes.