In order to study the mechanical behavior of steel-concrete composite beams with different shear connection degree， finite element models of composite beams are established. In addition， the validity and correctness of models are verified by four beam tests. Moreover， factors such as the number， diameter， length and material strength of the studs are selected to conduct the parametric study， by using the orthogonal test method. Furthermore， the influence of shear connection degree is discussed and the fitting formulas of bending capacity and end slip of composite beams are obtained. The results show that the number and diameter of studs have the most significant effect on the interface slip of composite beams. In addition， the bending capacity and beam end slip of composite beams with different connection degrees can be accurately predicted using fitting formulas. Moreover， in bridge engineering， as the studs are usually distributed according to structural requirements， the limit value of interface slip is not the controlling factor when designing composite beams.