Biological and ecological characters of Pieris rapae L. were investigated In Nghe An province. The following results were found: In culture medium of 29.2°C, 79.69 percent RH, their life cycle is 23.5 - 29.0 days: The egg stage is 3.18 +/- 0.049 days
the larval stage is 14.64 +/- 0.23 days
the pupal stage is 6.09 +/- 0.16 days. In culture medium of 24.76°C, 76.0 percent RH, the reproductive ability of Pieris rapae L. is 97.13 +/- 3,22 eggs/female in 11.33 days. In culture medium of 29.2°C, 72.0 percent RH, the reproductive ability of Pieris rapae Lis 150.4 +/- 26.19 eggs/female. In medium of 24.89 - 29.04°C, 71.97 - 76.00 percent RH and honey 50 percent, life span of adult male is 6.4 +/- 0.43 days, life span of adult female is 11.6 +/- 0.47 days.