Abstract: The high resistant larvae of diamondback moth (DBM)were collected from 4 different populations. The analysis results by GENEPOP software showed that the hypothesis of Hardy Weinberg equilibrium was rejected. There was systemic heterozygote deficit in these populations and existed genetic mutation in four populations. The results from esterase of Beijing diamondback moth suggested that the gene flow of the diamondback moth was due to the vegetables transportation with high frequency.