The heat shock protein 90 gene (hsp90) from Microplitis mediator Haliday was isolated through PCR, RACE and confirmed by semi-quantitative PCR. The results revealed that both heat shock and cold shock could induce the expression of Hsp90, no matter the larvae were under the condition of diapause, or not; The highest expression level appeared at the early stage of the 2nd-instar larvae, whereas the expression level decreased with development, the expression of Hsp90 increased after the adult eclosion. During the maintenance period under 4[degree]C, the expression of Hsp90 showed significant increment at the initial days but the level declined with the elongation of maintenance time. Microplitis mediator (Braconidae). Chinese none