Rare earth cerium (Ce), borosilicate mineral tourmaline and titanium dioxide (TiO₂) composite photocatalysts were prepared via a sol–gel method. Through detecting the microstructure and the methyl orange (MO) photodegradation of composite photocatalysts with different preparation processes and component contents, this paper discusses the effects of tourmaline and Ce on the preparation and photocatalytic activity of the composite catalysts. Among the different composite photocatalysts, the sample with the following addition sequence and proportions possessed the highest MO degradation ratio in 3 h (94.6%): 0.10 wt% of Ce was added into the primary alkoxide solution and 0.40 wt% of tourmaline added to the titanium sol, the synergistic effects on the microstructure of the photocatalyst resulted in nanoparticles wrapped around fine tourmaline particles during preparation and a high activity to photodegrade organic pollutants in water.