Objective:To detect the effect of extract of Camellia Sinensis (ECS) and extract of Camellia Ptilophylla Chang (ECPC) on DNA polymerase (Pol) of Ehrlich ascites tumor cells. Methods: Referring to the method of K.Ono, Pol was extracted from Ehrlich ascites tumor cells in mice. Pol α, β, and γ were separated by phosphocellulose column chromatography and were identified. The effect of ECPC and ECS on Pol was studied. Results: ECPC and ECS were shown to inhibit the activity of Pol α, β, and γ. IC50 values of ECS on Polα, β, and γ were 10.2μ g/ml, 9.9μ g/ml and 28.9 μ g/mlrespectively. IC50 values of ECPC on Pol α, Pol β and Pol γ were 5.6 μ g/ml, 15 μ g/ml and 14.7 μ g/mlrespectively. The modes of inhibition of ECPC on Pol α,Pol β and Pol γ were noncompetitive with respect to template DNA. The Ki values of ECPC on Pol α, β, and γ were 2.68± 0.12 μ g/ml, 2.24 ± 0. 12 μ g/ml , 2.56 ±0. 18 μ g/ml . Conclusion: ECPC and ECS were shown to have inhibitory effect on DNA polymerase of tumor cells. The mode of inhibition of ECPC on Pol α, Pol βand Pol γwere noncompetitive with respect to template DNA.