Abstract: The steel-concrete composite slab is becoming popular in the fields of building and bridge structures. Nevertheless, at present little study on the foundational performance of elastic stability of steel-concrete composite slab for all practical purposes is available, especially on its local buckling behavior. The maximal spacing of shear connectors (such as studs) is the most important factor to prevent the steel plate from local buckling before yielding, and it also makes steel plate and concrete slab behave as one. Based on model parameter analyses, the local buckling behavior of steel-concrete composite slab with simply supported edges in pure shear is studied by finite element methods. A calculating model steel plate with typical boundary is proposed to simulate the buckling performance of the steel plate surrounded by shear studs in the composite slab. The formula of maximal spacing of shear studs is deduced for the simply supported composite slab. The calculation result is slightly conservative.