Abstract: Phytophthora capsici was used as test material, the function of phospholipase D PcPLD8 gene was studied by gene silencing and gene overexpression, the effects of PcPLD8 gene on the growth and pathogenicity in P.capsici were revealed, in order to provide reference for further revealing the mechanism of phospholipase D in the pathogenesis of P.capsici.The results showed that the silenced transformants S1 and S5 of PCPLD8 gene had sparse hyphae, many and short lateral branches, small colony diameter and slow growth rate, the pathogenicity to Nicotiana benthamiana decreased obviously,compared with the wild-type strain WT and the empty vector transformant CK.And PCPLD8 over-expressed transformant OE2showed little change in hypha morphology,growth rate and pathogenicity to N.benthamiana.