Cu₂ZnSnS₄ (CZTS) is a narrow band gap, non-toxic, environmentally friendly semiconductor photocatalytic material. Cu₂ZnSnS₄ nanoparticles were synthesized by a hydrothermal method at different temperatures. XRD and Raman results showed that CZTS with a high crystallinity kesterite structure was successfully prepared. Photoelectrochemical tests showed that CZTS is a p-type semiconductor with a band gap of 1.5 eV, and its photocurrent density could attain 0.3271 μA cm⁻². It was found that CZTS had good photocatalytic activity for RhB via the photocatalysis of Rhodamine B (RhB) degradation with CZTS nanoparticles under visible light. The degradation efficiency of RhB by CZTS reached 98.20% within 90 min, and the degradation rate was about 0.02905 min⁻¹. The photocatalytic degradation mechanism of CZTS was studied through free radical capture experiments, and results showed that photo-generated electrons could react with O₂ and H₂O in the solution to form ˙OH, which degraded RhB into H₂O and CO₂.