Morphology control of metal sulfides has always been of great significance in the application as anode for sodium ion batteries (SIBs). In this paper, the microstructure of WS2 nanosheets were controlled by tailoring different sulfur sources, obtaining a small size and few-layered product by thioacetamide (TAA) finally. Results show that the size of WS2 nanosheets plays a significant role in the Na-ion storage. Small size and few layered WS2 nanosheets prepared with TAA exhibit the capacity of 261mA h g−1 at the current densities of 100mAg−1 and 226mA h g−1 at 700mAg−1, which is obviously higher than that of other WS2 samples. This difference of Na-ion storage performance mainly depends on the insertion reaction mechanisms of Na-ion during the charge/discharge process in diverse layered structures. It can be found that the small size and few layered structure can significantly improve the Na-ion storage with inserted into WS2 interlayers. We believe that this work will inspire the fabrication of layered structure transition metal dichalcogenides as anode materials for SIBs.