Abstract: Field and cage experiments on transmission of Nosema locustae disease in grasshopper populations were conducted in grassland of Qinghai province. The results showed that the number of spores on the leaves of grass decreased with the time after application. And the species of grasshopper occurring early in the season, infected by N. locustae could transmit the disease to the species occurring late by 26 67%. The reduction of grasshoppers was more than 56 45% 30d after treatment with this pathogen and the infection of the survivors was 28%.