In order to reveal the failure mechanism of precast prefabricated composite beams with shear group studs, an experimental study on the push-out failure of prefabricated shear group studs with three specimens was carried out. The typical failure characteristics such as deformation, slip, crack development and stud failure are obtained by push-out test and the interaction between stud and concrete is analyzed by numerical method. The results show that the whole loading process can be divided into linear elastic stage and plastic failure stage. The specimens are ductile failure which indicates that the interface cracks around the reserved hole appear first, then the precast concrete cracks downward at the corner below the reserved hole and finally all or most of the studs are sheared. The stud is broken under the combined action of bending and shearing, what’s more, the behavior of the stud in the assembled shear group stud is slightly weaker than that of the cast-in-place group stud. It is suggested that the appropriate reduction should be made in the standard calculation, and the assembly reduction factor of 0.85 can be taken.