Abstract: To investigate the effects of deltamethrin on male Asian corn borer (Ostrinia furnacalis) to perceive sex pheromone, the electro physiolgical and behavioral response of topically treated male Asian corn borer to sex pheromone were tested with EAG sets and wind tunnel. The results showed that the summit response of male moths to varied ratios of pheromone blends was at E/Z=1/9,5/5 and 9/1, which was similar to that of control, but the EAG values were only 0.25mV to 0.45mV, which were significant lower than control by 0.15mVto 0.35 mV. The low threshold dose of pheromone for treated males to perception was 1ng, and the highest was 10000ng, which was also similar to control, but low by 0.1mVto 0.5mV in EAG values. This suggested that deltamethrin mainly affected the sensibility of peripheral reception system, while the preliminary recognition to the ratio of pheromone blends by peripheral reception system are not disturbed heavily. In wind tunnel test, a relative higher amount of males shifted to response to pheromone with E/Zratios of 7/3 from E/Z =1/1 of control males, and keep on response at this level to blends with more E1214:OAc. The lowest dosage of pheromone effectively elicited response of males also shifted from 10ng to 100ng, and the highest doses for response declined to about 50000ng from 100000ng of control, which might result in a narrower band of effective doses. It is suggested that the sublethal dosage of deltamethrin not only affected the sensibility of male moth to perceive the pheromone, but also affected the specificity of pheromone perception.