Abstract: In order to screen out effective fungicides against grape Botrytis cinerea, and lay a basis for grape Botrytis cinerea prevention and compounded preparation, the toxicities of fungicides like pyraclostrobin, fludioxonil, cyprodinil and boscalid against grape Botrytis cinerea were tested by mycelium growth rate method, and the synergistic effect of pyraclostrobin and fludioxonil was studied. The results of the toxicity determination showed that the 4 fungicides had inhibiting effect on grape Botrytis cinerea, fludioxonil had the best toxicity with EC 50 value of 0.0845 mg/L, then were pyraclostrobin and cyprodinil with EC 50 values of 3.6023 and 5.6300 mg/L, respectively. Boscalid had the lowest inhibiting effect withEC 50 value of 68.2860 mg/L. The result of the allied toxicity determination showed that EC 50 values of 5 compounded preparations of pyraclostrobin and fludioxonil were 0.3483, 0.5291, 0.5741, 1.8751 and 3.9185 mg/L, and the values of cotoxicity coefficient were 397.50, 166.64, 28.75, 4.85 and 2.24, respectively. The addition effect was most obvious when the mass ratio of pyraclostrobin and fludioxonil was 1:25, and the value of co-toxicity coefficient was 397.50.