Abstract: The variation regularity of esterase (EST) zymogram in brown planthopper (Nilaparvata lugens Stal) population during rice-growing stages or at different habitats was studied.The results showed that there were three bands designating as A, B and C bands with transferring rates of 0.4102, 0.4709 and 0.5042 respectively, which composed four zymogram types, i.e.I -c, II -BC, III -AC and IV-ABC, in EST zymo-gram of brown planthopper population.In the rice-growing season, the brown planthopper population was consisted of different individuals possessing these four zymogram types, and formed the population heterogeneity.At the begining of population establishment (in May), the rate of type I (0.46) was lower, it increased with the population development and maintained stably around 0.6.In November, the terminal of rice-growing season, the rate of type I went up to 0.9, there were also significant differences of the EST zymogram in N.Lugens among the samples from black lig’lt trap, lower part of rice plant and artificial propagation under caged condition.The analysis results showed that higher proportion of type I indicates the more healthy situation of brown planthopper population.