The capacity and stiffness of the steel frames are improved significantly considering slab composite effect which may cause bad effects on the seismic.Efficient and accurate FEM of ABAQUS was proposed for numerical simulation.And the selection of elements types, the material stressstrain relationship and damage model were made a detailed description.Nonlinear finite element model was approved with existing steel framecomposite connections quasistatic test home and abroad.It is shown that the capacity of this type connections is improved by nearly 26% and the stiffness by 30%.And this type of connections have more full hysteretic curve with high energyconsuming ability and good seismic performance.