Abstract: Steel tube slab (STS) components were adopted to construct a subway station in Shenyang Metro, whose load-carrying capacity has a significant impact on the whole project. Based on a flexural experiment of six simply supported STS specimens under four-point bending, this paper investigated the failure process and crack development of STS specimens, and obtained the load-deflection curves. The effects of the spacing between the tubes, concrete compressive strength and transverse connecting modes of tubes on the flexural capacity were studied. Based on the numerical simulation using ABAQUS software, a numerical model was established to investigate the effects of flange thickness, steel tube thickness on the flexural capacity of STS structures. According to the calculated results, the reasonable range of the ratio of flange to steel tube thickness is obtained. The research achievement will provide a theoretical support for the design of STS structures.