Abstract: In the second generation of Heliothis armigera Hubner season, 20% chlorpyrifos EC that can easily seep into the body of the insects is of great effect. The experiment shows that the correcting effect of the prevention and control reaches respectively 83.99%, 89.08% and 89.73% when 18g effective composition of it is employed on 667 m2 field in 1 day, 3 days and 7 days, and compared with 120ml 12% lulutong EC employed on 667m2 field, its effect is more quick and lasting. In terms of protecting the top of the stem, when 18g effective composition of 20% chlorpyrifos EC is employed on 667 m2 field, the effect is 89.30, which is remarkably better than that of 120ml 12% lulutong EC employed on 667m2 field.