Prefabricated steel-concrete composite structure is widely used in bridge engineering, and the research on mechanical behavior of prefabricated assembled cluster nail shear key is of great significance to the safety application of prefabricated steel-concrete composite bridge. In order to find out the influence of the number of groups on the mechanical properties of shear keys, the push-out loading tests of single key group and double key group are carried out. The load-slip curve, failure form and shear capacity of the group specimens, combined with the numerical simulation of the three-bond group and four-bond group specimens, are used to study the bearing capacity reduction effect of the assembled shear key under the multi-bond group. The results show that the failure modes of the single bond group and the double bond group shear bond are both stud shearing, however, the number of cracks of the single bond group specimen is less than that of the double bond group specimen. Meanwhile, it is the fact that the reduction effect of bearing capacity increases with the increase of the number of bond groups, and the non-uniform phenomenon between bond groups is gradually significant with the increase of load. Based on the energy method, the bearing capacity reduction effect of multi bond group due to uneven force is analyzed, and a simplified formula of bearing capacity reduction factor is proposed. The research