Objective To investigate the interspecific competition between Bemisia tabaci and Myzus persicae.Method Three different interspecific competition ratios (1:1, 1:5 and 1:10) were established under the condition of (26±1) ℃. The development time, survival rates, adult longevity and fecundity of B. tabaci and M. persicae were investigated.Result For B. tabaci, interspecific competition prolonged the development time of 1^st and 2^nd instar nymphs, but had little effect on the developing rate of the whole nymphal stage. The 1:1 and 1:5 ratios of B. tabaci to M. persicae had little effect on the survival rate of B. tabaci nymphs, shortened the longevity of adult female, and caused a reduction in fecundity of adult females. The 1:10 ratio of B. tabaci to M. persicae clearly reduced the survival rate of B. tabaci nymphs, extended the longevity of adult females, and increased the reproductive capacity of their offsprings. For M. persicae, interspecific competition clearly prolonged the developmental time of nymphs and reduced the survival rate of nymphs. The 1:1 and 1:5 ratios of M. persicae to B. tabaci shortened the longevity of M. persicae adult, while had little effect on female fecundity. The 1:10 ratio of M. persicae to B. tabaci significantly prolonged the longevity of M. persicae females, while reduced female fecundity.Conclusion Interspecific competition between insects with overlapping niche has a great impact on the population dynamic of insects, and sometimes even causes competitive replacement.