Abstract: Abstract: Sporulation and protoplast of Paecilomyces fumosoroseus was induced by ultraviolet ray, biological characteristics and virulence of induced isolates was determined. The result showed : conidia yield of UV-22 and UVP-39 was respectively 1.58 and 1.37 of CK, virulence raised respectively 14.3% and 11.00%,and inducing effect of Sporulation was better than that of protoplast.