One virus of Diprion nanhuaensis was separated from the died D. nanhuaensis, the virus belongs to nuclear polyhedrosis virus, bacilliform virus particle in inclusion body appears SNPV(single nucleocapsid polyhedrosis virus) by electron microscopy. The structure of inclusion body appears polyhedron and close to rotundity, and the length of diameter of inclusion body ranges 0.5～1.0 μm, a little proportion of them shows anomalistic form. There are many bacilliform virus particles in one inclusion body. Six virus particles in one inclusion body take up a large proportion and one virus particle in one inclusion body only takes up a small proportion, the length of virus particle ranges 125～200 nm,and the length of diameter of virus particle ranges 25～30 nm. Meanwhile,the virus can infect the 2～3 instars Neodiprion xiangyunicus and the 2～3 instars D. nanhuaensis in laboratory.
