Abstract: Renewable energy interconnection and electricity market operation is the development trend of electric power industry. One of the technological problems of power dispatch and exchange center is how to calculate the available transmission capability (ATC) accurately and timely in the power market. An ATC calculation model and its solution method, considering wind generator in bilateral power market, was proposed in this paper. The power flow model with wind generators, generator capacity, node voltage, and thermal stability limits were introduced to the constraints of the proposed ATC model. According to the characters of bilateral power market, the computational steps of ATC were also described. The Simulation results of 19-buses power network showed that the new bilateral trade in power market had significant influence on ATC, the electric power system dispatcher must update ATC on time, and adjust market transaction according to the new ATC.