The control effect of Trichogramma on Chilo suppressalis in different generations occurrence areas was compared in Jilin Province. It was found that the survey values in one generation region were higher than that in two generations region. It is considered that only the first generation of Chilo suppressalis were controlled in two generations region, the second generation of Chilo suppressalis still gave rise to harm, resulted in the low survey values of Trichogramma control effect. Therefore, the investigation method of Trichogramma control effect should be improved. The control effect difference of treatments that both two generations treated by Trichogramma and the first generation treated only were also tested in two generations region. The results showed that the control effect of both two generations treatment was about 10% higher than the first generation treated only, and control both generations could reduce the number of overwintering live insects and effectively reduce the number of population in the second year, so it is suggested that both two generations of Chilo suppressalis should be controlled in two generations region.