Abstract: For further investigate the insect community structure in rice growing season in Jiande area, and know its effect on rice growing. From May to October 2012, a systematic investigation of the insect communities under the lamp in rice field in Jiande, Zhejiang Province was carried out by employing natural ecosystem classification, ecological function classification, the degree of dominance classification, the diversity index of the insect communities in different time and degree of uniformity. The results showed that: the whole insect community in Jiande consisted of 69 species, belonged to 13 orders. And among them, Lepidoptera was the dominant order which made up 26.09%. Homoptera came second, made up 17.39%, and Coleoptera was 14.49%. The insect community was divided into four function parts through ecological function classification. Here we ignored the medical insects which had the lest affect to the rice. Phytophagous insect was the largest part, account for a large proportion in number, and had the greatest effect on rice yield. The dominant species were Anopheles, made up 48.58%, Brown Planthopper was 15.01% and Sogatella Furcifera was 12.03%. Brown Planthopper, Sogatella Furcifera and Rice Leaf Folder belong to R-class pests, they were small and their quantity were influenced greatly by environmental climate, and comparatively speaking, they did a more serious damage to rice, they played a decisive role in community structure. The insect community diversity index (H') and evenness (J) were the highest in May, this suggested that the insect community structure in rice field was the most stable and the balance among species was the best in May. As the month goes on, insect community diversity index (H') and evenness (J) had also been gradually reduced. These results provided important theoretic basis for IPM in the rice field, at the insect community level.