To provide a scientific basis for proper application and conservation as well as utilization of the dominant natural enemies, in this paper, the quantity, time and space framework of Sogatella furcifera (Horvath), Laodelphax striatellus(Fallen), Nilaparvata lugens (Stål) and their predatory natural enemies were systematically studied using grey system analysis, ecological niche analysis and aggregated-intensity index analysis of spatial patterns in both control and non-control paddy fields of rice variety "Two Excellent 0923". The same methods were also used to analyze the impact of pesticides on predatory natural enemies of three species of planthoppers. The synthetic ranking results indicated that, in non-control field, the orders of main natural enemies of Sogatella furcifera (Horvath), Laodelphax striatellus(Fallen) and Nilaparvata lugens (Stål) were, respectively, Plexippus setipet (Karsch), Erigonidiun graminicolum(Sundevall) and Tetragnatha maxillosa (Thoren); Theridion octomaculatum(Boes et str.), Neoscona theisi (Walckenaer) and Tetragnatha maxillosa (Thoren); Marpissa magister (Karsch), Singa pygmaea (Sundevall) and Cyrtorhinus lividipennis (Reuter). In control field, the orders of main natural enemies of Sogatella furcifera (Horvath), Laodelphax striatellus(Fallen) and Nilaparvata lugens (Stål) were, respectively, Plexippus setipet (Karsch), Erigonidiun graminicolum(Sundevall) and Tetragnatha maxillosa (Thoren); Pirata subpiraticus (Boes et Str), Singa pygmaea (Sundevall) and Erigonidiun graminicolum(Sundevall); Cyrtorhinus lividipennis (Reuter), Pirata subpiraticus(Boes et Str) and Singa pygmaea (Sundevall). The comparing analyses showed that the top three dominant natural enemies of Sogatella furcifera (Horvath) were identical, and in those of Nilaparvata lugens (Stål) only Cyrtorhinus lividipennis (Reuter) and Singa pygmaea (Sundevall) were same, whereas those of Laodelphax striatellus(Fallen) were completely different between the control field and non-control field by beat-pan method. Compared to the beat-pan method, the top three dominant natural enemies of Laodelphax striatellus(Fallen) were identical, whereas there were two same kinds of natural enemies, i.e. Tetragnatha maxillosa (Thoren) and Singa pygmaea (Sundevall) in those of Sogatella furcifera (Horvath), and Marpissa magister (Karsch) and Plexippus setipet (Karsch) in those of Nilaparvata lugens (Stål) between the control field and non-control field. The differences of these dominant natural enemies between two kinds of paddy fields were mainly caused by using pesticides, which kill and wound the three species of planthoppers, so pesticides affected the occurrence of natural enemies. In the non-control field, there was only a same kind of natural enemy (Tetragnatha maxillosa (Thoren)) in the top three dominant natural enemies of Sogatella furcifera (Horvath) and Laodelphax striatellus(Fallen), and Marpissa magister (Karsch) in those of Nilaparvata lugens (Stål) between beat-pan method and sweep net method. However, in the control field, the same natural enemies in the top three dominant natural enemies of Sogatella furcifera (Horvath) was only Tetragnatha maxillosa (Thoren), but no same natural enemies were found in those of Laodelphax striatellus(Fallen) and Nilaparvata lugens (Stål). The difference seems to be mainly caused by the two different investigation methods.