Abstract: Tomato late blight is one of the most harmful fungal diseases in tomato production,which has great influence on the yield and quality of tomato. At present, the most effective control method is still to breed tomato varieties containing late blight resistance genes. By establishing efficient molecular marker system of tomato late blight, tomato resistant materials against late blight were quickly screened. The optimized molecular markers DM1, R2M1S, PH3-GL-R/S and TG328 were used to select51 materials containing resistance gene Ph-3. The results of DAB and NBT staining showed that the accumulations of H₂O₂ and O₂^- in leaves of 21P61 and 21P70 resistant materials were higher than those of susceptible materials. The resistance material 21P70 was identified by qRT-PCR in response to the expression of resistance gene Ph-3. However, tomato material 21P61 was inconsistent with the resistance pattern of Ph-3, which supposed that 21P61 might contain other resistance gene backgrounds.