It is still a great challenge to develop photocatalysts with high efficiency and low cost to reach the scale of industrialization. In this work, we prepared an S-type heterojunction photocatalyst with Co3S4 nanoparticles supported on g-C3N4/alpha-Fe2O3. Characterizations, such as PL, UV-vis, electrochemical impedance spectroscopy, and linear sweep voltammetry, proved that the composite material had excellent photoelectrochemical performance and good stability. The hydrogen evolution amount of g-C3N4/alpha-Fe2O3/Co3S4 is as high as 191.41 mu mol, which is about 30 times that of pure Co3S4 (6.38 mu mol). The improvement performance of a composite material could be attributed to the following points: the EY molecules not only increase the light absorption rate of the samples but also act as electron donors; the highly dispersed Co3S4 nanoparticles provide a large number of reduction sites; and the constructed S-scheme heterojunction consumes useless electrons and holes in the hydrogen production system and utilizes the strong redox potential of the composite material to promote the separation of photogenerated carriers. In particular, Co3S4 nanoparticles with different degrees of dispersion were prepared by changing the preparation sequence of the composite catalyst. The design ideas of this experiment can provide an effective reference for the synthesis of efficient and stable multiple photocatalyst systems.