Abstract: The ATC computation makes use of Continuation Power Flow (CPF) and sensitivity method, and is carried out under different operation conditions with the tool of VSAT. From the results of considering different HVDC operation situations under the typical operating mode, there will be larger inter province ATC after Xinjiang Power Grid is connected and the commission and operation of all HVDC projects. There will be stronger power exchange capability if increasing the capacity of export power transmission passages after forming 750kV main power grid structure. The analysis can supply reference for the future plan and operation security of the Northwest power system.