Abstract: The toxicity of 9 fungicides against pepper phytophthora blight were tested with mycelium growth rate method. The results indicated that the highest toxicity of fungicides were dimethomorph (EC50=0.48 滋g/mL) and fluopicolide (EC50 =0.32g/mL). The synergisms were chosen by the method of co -toxicity coefficience, and the ratios were that chlorothalonil /fluopicolide (1-9) and dimethomorph/fluopicolide (2-8). The 20% suspension concentrates (SC) were prepared with best synergism ratio. After 10 d treatment, the pot experiment reuslts showed that the control effect of dimethomorph/ fluopicolide 20% SC diluted 2 000 times was up to 96%; the control effect of chlorothalonil/fluopicolide 20% SC diluted 1 000 times was 75%. Statistic analysis indicated that the control effect of dimethomorph/fluopicolide 20% SC diluted 2 000 times was equal to dimethomorph 50% SC diluted 1 000 times and higher than that of 68.75% Infinito SC diluted 1 000 times significantly.