Abstract: In order to evaluate the ecological risk of insecticides to the tobacco (Nicotiana tabacum L.), the contents of chlorophyll and carotenoid in tobacco seedling leaves treated with the four insecticides were measured. When the tobacco seedlings at nine-leave stage which were raised under greenhouse condition, the contents of chlorophyll and carotenoid of the ninth leave were tested after treated with 100μl of the four insecticides. The result showed that the contents of chlorophyll a, chlorophyll b, the total chlorophyll and carotenoid of the tobacco seedling leaves treated with avermectins, imidacloprid and acetamiprid increased, the ratios of Chla / Chlb decreased. The contents of chlorophyll a, chlorophyll b, the total chlorophyll and carotenoid of the tobacco seedling leaves treated with emamectin benzoate decreased, the ratios of Chla/Chlb increased. Therefore, avermectins, imidacloprid and acetamiprid insecticides are safe to the tobacco, and emamectin benzoate can cause adverse effects.