Rational design and synthesis of heterostructures based on transition metal dichalcogenides (TMDs) have attracted increasing interests because of their promising applications in electronics, catalysis, etc. However, the construction of epitaxial heterostructures with an interface at the edges of TMD nanosheets (NSs) still remains a great challenge. Here, we report a strategy for controlled synthesis of a new type of heterostructure in which TMD NSs, including MoS2 and MoSe2, vertically grow along the longitudinal direction of one-dimensional (1D) Cu2-xS nanowires (NWs) in an epitaxial manner. The obtained Cu2-xS-TMD heterostructures with tunable loading amount and lateral size of TMD NSs are achieved by the consecutive growth of TMD NSs on Cu2-xS NWs through gradual injection of chalcogen precursors. After cation exchange of Cu in Cu2-xS-TMD heterostructures with Cd, the obtained CdS-MoS2 heterostructures retained their original architectures. Compared to the pure CdS NWs, the CdS-MoS2 heterostructures with 7.7 wt % loading of MoS2 NSs exhibit the best performance in the photocatalytic hydrogen evolution reaction with a H2 production rate up to 4647 μmol·h-1·g-1, about 58 times that catalyzed with pure CdS NWs. Our synthetic strategy opens up a new way for the controlled synthesis of TMD-based heterostructures, which could have various promising applications.