A field test for controlling soybean pod borer, Leguninivora glycinivorella (Mats.), with 2.5％ deltamethrin was conducted to compare the effect of applications among the initial stage, the peak stage and the post peak stage during moth flight period in Gongzhuling, JJlin Province, China, in 1935 and 1986. The result showed that rates of injured grains were 4.32％ and 3.15％ and rates of injured pods were 3.97％ and 2.6％ respectively for the Check in 1985 and 1986; while the rates of injured grains and pods were less than 1％ on all applications of the different dates on both years. Nevertheless, all of the differences between the effects of applications at different dates was not significant. It is considered that deltamethrin active ingredient 0.8g./mu (12 g./ha) was applicated once during the moth flight period (about first half of August), the damage from soybean pod borer should be controlled.