[Aim]  To determine the effects of different green manure crops on the population dynamics of the main pests (Grapholita molesta, Adoxophyes orana and Apolygus lucorum), and their natural enemies (syrphid flies, Harmonia axyridis, Propylaea japonica, lacewing  and ichneumon wasp), in pear orchards on the North China Plain. [Methods]  The dynamics of the main pests and their natural enemies on Orychophragmus violaceus, Elymus dahuricus, Vicia villosa, natural grass and clean tillage, were investigated over 2 years in pear orchards in Leichen, Jinzhou, Shijiazhuang. [Results]  The relative abundance of G. molesta on different green manure crops was as follows: E. dahuricus < V. villosa < natural growing grass < O. violaceus < clean tillage, and the relative abundance of A. orana on these was: E. dahuricus < O. violaceus < natural growing grass < V. villosa < clean tillage. These two pest species were most common in pear orchards with clean tillage. Compared to the latter, the average abundance of these pests in orchards with green manure crops was 52.41% and 33.86% lower, respectively. A. lucorum was most common in V. villosa in pear orchards. Numbers of syrphid flies, ladybirds, Chrysopidae, and parasitic wasps were higher in orchards with green manure crops than in those with clean tillage; especially those with legumes, grass and V. villosa, which attracted the most syrphid flies, P. japonica and Ichneumonidae, but the difference was not significant (P＞0.05). [Conclusion]  Sowing green manure crops between rows of trees in pear orchards on the North China Plain can significantly decrease the abundance of G. molesta and A. orana. A. lucorum was most common in orchards with V. villosa. In such orchards A. lucorum should be controlled during key production periods. In addition to having fewer pests, orchards with green manure crops also had significantly more of the natural enemies of these pests, such as, syrphid flies, H. axyridis, P. japonica, Chrysopidae, Ichneumonidae.