Abstract: Abstract: Under the condition of culture dishes rearing and gauze-cage rearing, the influence of interspecies competition on Leis axyridis, Propylaea japonica (Thungberg) and Chrysopa pallens ,which were three kinds of predatory natural enemies of aphids in forest field were studied. The results indicated that three kinds of larvae killed each other in the Petri dish space, the 1st instar larvae of L. axyridis and C. pallens were higher survival rate, and they could prey on P. japonica larvae. After 2nd instar larvae of L. axyridis was relatively dominant, which preyed on other two kind of larvae. In contrast, relatively large space with a gauze-cage, L. axyridis larvae and C. pallens larvae were relatively higher survival rate under the condition of more preys, P. japonica larvae was increased with age. Yet, C. pallens had higher survival rate under the condition of less preys, others were lower. Based on the research of adult stage, it showed that P. japonica taken prey in the shortest time under a common place, but C. pallens taken the longest time. Minimal disruption to L. axyridis, it preyed largest number of aphids, obviously, compared with other two kinds of adult stage, L. axyridis was dominant species.