Abstract：Prochloraz’s activities on inhibiting the mycelium growth of Trichoderma viride and 5 different varieties of Pleurotus ostreatus（Jacq：ex Fr.）Quèl.?were tested by the mycelium growth rate method and its effect on conidiophore germination of Trichoderma viride was tested by inhibition zone method．The results indicated that prochloraz could remarkably inhibit the growth of Trichoderma viride mycelium and spore germination．The EC50 values were 2.536 mg·L-1 and 5.482 mg·L-1，respectively. Additionally，prochloraz could also inhibit the growth of Pleurotus ostreatus（Jacq：ex Fr.）Quèl. mycelium．There are less significant differences of inhibition to Pleurotus ostreatus（Jacq：ex Fr.）Quèl. when the effective concentration of prochloraz was below 8.333 mg·L-1，its inhibitory effect on the growth of Pleurotus ostreatus（Jacq：ex Fr.）Quèl.?mycelium was not remarkable．
