To conserve and utilize natural enemies for comprehensive control of insect pests in peach orchards, the seasonal and annual variations of population quantities of four insect pests with their natural enemies in "518" nectarine orchard were systematical investigated. The results of a paired t-testing showed that the t values of four main pest numbers, i.e. Empoasca flavescens, Myzus persicae, Tetranychus viennensis and Cleoporus Variabilis, were, respectively, 0.8049、1.1449、0.0700、0.9895, whilst the t values of eight natural enemy numbers, i.e. Harmonia axyridis, Propylaea japonica, Clubiona japonicola, Theridion octomaculatum, Misumenops tricuspidatus, Erigonidium graminicola, Chrysopa Sinica, Epistrophe balteata, were, respectively, 1.7014、0.9098、1.4304、0.0639、0.1545、0.0544、1.5579、0.8249 between the two spring-summer seasons of 2009 and 2010, which all are significantly lower than 2.26 (t_0.05 value), indicating that no significant differences existed in the numbers of four insect pests and their natural enemies between the two spring-summer seasons in "518" nectarine orchard. The further analysis indicated that the t values of Myzus persicae and Clubiona japonicola were, respectively, 38.8150 and 9.1706 with t>t_0.01 (3.355), and the t values of Harmonia axyridis, Misumenops tricuspidatus, Epistrophe balteata were, respectively,2.3332, 3.1497 and 2.4712 with t>t_0.05(2.306),indicating that there were significant differences in their numbers between the spring-summer season and the autumn season of 2009 in "518" nectarine orchard. Moreover, there was also highly significant difference in the numbers of Clubiona japonicola (t=7.0763, P<0.01) between 2010 spring-summer season and 2009 autumn season in "518" nectarine orchard, whereas no significant differences existed in the others. The quantity, time and space framework of Myzus persicae, Empoasca flavescens, Tetranychus viennens, Cleoporus variabilis and their predatory natural enemies in 2009 spring-summer season and autumn season, as well as 2010 spring-summer season were systematically studied using grey system analysis, ecological niche analysis and aggregated-intensity index analysis of spatial patterns. The synthetic ranking results indicated that, in 2009 spring-summer season, the orders of main natural enemies of Empoasca flavescens, Myzus persicae, Tetranychus viennensis, and Cleoporus variabilis were, respectively, Harmonia axyridis, Theridion octomaculatum and Propylaea japonica; Chrysopa Sinica, Clubiona japonicola and Harmonia axyridis; Erigonidium graminicola, Misumenops tricuspidatus and Propylaea japonica; and Erigonidium graminicola, Theridion octomaculatum and Propylaea japonica. In 2010 spring-summer season, the orders of main natural enemies of the four pests were, respectively, Propylaea japonica, Theridion octomaculatum and Erigonidium graminicola; Chrysopa Sinica, Epistrophe balteata and Clubiona japonicola; Theridion octomaculatum, Erigonidium graminicola and Propylaea japonica; and Erigonidium graminicola, Theridion octomaculatum and Harmonia axyridis. In 2009 autumn season, the orders of main natural enemies of the four pests were, respectively, Propylaea japonica, Erigonidium graminicola and Harmonia axyridis; Theridion octomaculatum, Harmonia axyridis and Clubiona japonicola; Misumenops tricuspidatus, Propylaea japonica and Theridion octomaculatum; and Erigonidium graminicola, Theridion octomaculatum and Misumenops tricuspidatus. In addition, our results also showed that the λ values of gathering average of all four insect pests, i.e. Empoasca flavescens, Myzus persicae, Tetranychus viennensis, and Cleoporus variabilis, were greater than two, indicating that the aggregation of insect pest was caused by itself. The λ values of gathering average of some natural enemies, i.e. Harmonia axyridis and Chrysopa Sinica in May 5, 2009 as well as Erigonidium graminicola in June 18, 2009, were also greater than two. However, the λ values of gathering average of most natural enemies were less than two, implying that the aggregation of most natural enemies was caused by different environmental factors. These above results might provide an important foundation for further protecting natural enemies and optimizing control strategies of the four major insect pests in peach orchard.