Based on the interior point methods， an implementation scheme of security constrained optimal power flow（SCOPF） algorithm is presented. To improve the computation efficiency， a strategy of enforcing or releasing binding contingencies and detecting infeasible contingencies is discussed. According to the special bordered-blocked-diagonal-form of the reduced KKT system， a decomposition and coordination algorithm for solving SCOPF correction equations is deduced. To provide contingency screening results for SCOPF in energy management system， an interface between the security analysis function and the SCOPF function is designed according to this special implementation. Numerical tests on IEEE systems reveal the characteristics of the algorithm. The economy and security comparison between OPF and SCOPF results suggests the necessity of incorporating steady-state security constraints into classical OPF model.