Abstract: In order to optimize the seam details of the assembled composite slabs, the experimental study and finite element analysis were carried out on the edge composite slabs, in which the steel bars at the mid-span joints of precast bottom slabs were bent upwards and additional steel bars were arranged. The influence of the diameter of the additional steel bars and the thickness of the prefabricated slab in the composite area on the bearing capacity of slab was discussed. The results show that the failure pattern of the composite slabs is a typical flexural failure, and the flexural bearing capacity of the composite slabs can be equivalent to that of the cast-in-situ slab. By changing the diameter of the additional steel bars and the thickness of the prefabricated slab in the composite area, the ratio of ultimate load simulation value to calculated value of the composite slabs is between 1.04 and 1.09, and the ultimate bearing capacity of the composite slabs can reach the same effect as equivalent cast-in-place. Measures such as additional steel bars with the 0.8l_ab lap length and bent-up bars of the precast bottom slab can effectively transfer forces without tearing failure on the composite surface.