An integrated security analysis and optimal power flow package has been implemented in the North East China Power System Control Center. the functions imple-mented in this package include Stata Estimation, Short-Term Load Forecast, External Network Equivalent, Automatic Contingency Selection, Security Assessment and Correction. Oprimal Power Flow. This paper intro. duces, in some details, the functions implemented, the algorithms adopted in the package and the real-time oper-ation experiences. The outstanding featrue of the packageis that it integrates the security and optimization together to get a better merit. The improved ACS algorithm in this paper is a sensitivity based one with bOth real power overload and voltage violation considered. The security as-sessment function is based upon a sparse vector factor modification and both branch outages and generator outages are considered in the algorithm. A P-Q Alternate Approximating OPF algorithm is proposed in this paper and implemented in the package. The formulation of the OPF algorithm is given. The application of this package toNorth East China Power System is described and the oper-ation experiences are given.