Pesticide residuals in agricultural products threaten human health. A new solution to this problem was to use potocatalytic degradation agent to degenerate these residuals. This paper explored the photocatalytic effects of nanometer TiO2 both in powder and hydrogel forms in degenerating chlorpyrifos residual in apples and damsons. The results showed that both powder and hydrogel forms work well. However, Hydrogel form was more effective than powder form. Because it was innoxious and highly photo catalytic, TiO2 has broad development prospects as a photocatapytic degradation agent to degenerate pesticide residuals in agricultural products.