According to quantum size effect and interface defects theory, the phase-modificate defects engineering photo catalyst MoS2/CdS-1/CdS-2 with smaller lattice mismatch degree was successfully designed through simple hydrothermal and solvothermal methods, in which sphalerite CdS-1 was nanoparticle (NP) while wurtzite CdS-2 was nanosheet (NS) shaped. The results showed H-2 evolution activity was increased, which was about 20 times and 30 times those of MoS2/CdS-1 and MoS2/CdS-2, respectively. Also of note, it was 600 times and 900 times compared to CdS-1 and CdS-2, respectively. According to the calculation results, there were less interface states because of smaller lattice mismatch degree. The absorbance was enhanced by realizing more than once it reflects and absorbs ray. The scope of ray absorption was extended on account of the quantum scale effect. It is hoped to fundamentally enhance the photocatalytic activity of CdS through self-modifying and defects engineering.