The invention discloses a tin disulfide coated titanium dioxide composite photocatalyst. The tin disulfide coated titanium dioxide composite photocatalyst is prepared by taking tin chloride pentahydrate, butyl titanate and thiourea as raw materials and absolute ethyl alcohol as a solvent by adopting a one-step solvothermal method, wherein the mass ratio of tin disulfide to titanium dioxide is (0.46 to 0.62) : 1.The composite photocatalyst is controllable in size; the flower-shaped tin disulfide evenly grows on titanium dioxide microspheres, and the photocatalyst material has relatively high light degradation efficiency on organic pollutants, such as rhodamine B, in the water body. The invention further discloses a preparation method for the tin disulfide coated titanium dioxide composite photocatalyst. The preparation method comprises the following concrete steps: mixing the tin chloride pentahydrate, the absolute ethyl alcohol, the butyl titanate and the thiourea to obtain mixed solution; performing hydrothermal reaction on the mixed solution, and then drying in a drying oven to obtain the tin disulfide coated titanium dioxide composite photocatalyst.