The electronic structure and optical properties of van der Waals heterostructures with different layers of MoS2 and VS2 stacks were studied by first-principles calculations based on density functional theory. The stability of two heterojunctions at room temperature was verified through ab initio molecular dynamics. In addition, both heterojunctions exhibit p-type Schottky contact. But compared to the heterojunction composed of monolayer MoS2, the barrier height in the heterojunction formed by the stacking of bilayer MoS2 and VS2 significantly decreases from 0.36 eV to 0.08 eV, effectively forming a low contact resistance and reducing the energy loss of carrier transport. The calculation of the light absorption spectrum indicates that the heterojunction composed of bilayer MoS2 has higher absorption peaks. The research results provide a theoretical basis for the design of heterojunctions based on MoS2 and their applications in high-performance optoelectronic devices.