The invention discloses a preparation method for TiO2/Sb2S3 composite photocatalytic colloid. The preparation method comprises the following steps: selecting titaniferous salt to serve as a precursor for hydrolyzing and synthesizing TiO2 colloid, wherein the hydrolyzing temperature is 10 to 90 DEG C; selecting sulfuretted hydrogen to serve as a sulfur source to be hydrolyzed and synthesized into Sb2S3 colloid with antimony oxide, wherein the hydrolyzing temperature is 10 to 50 DEG C; dialyzing the TiO2 colloid and the Sb2S3 colloid after mixing and stirring to obtain TiO2/Sb2S3 composite photocatalytic colloid. The colloid prepared by a distributed gelling method has the advantages of uniform distribution, mild and controllable reaction conditions, and easiness in operation; the TiO2/Sb2S3 composite photocatalytic colloid has higher solar light utilization rate and higher oxidizing-reducing capability.