By using cis-3-hexenyl acetate as standard chemical, the electroantennogram (EAG) responses of Maruca testulalis (Lepidoptera, Pyralididae) to plant volatiles and sex pheromone were investigated. Both the males and the females of M. testulalis showed strong EAG responses to the volatiles, but no significant difference was observed under most test concentrations. Among the test nine plant volatiles, the males and females had greater difference in the shape of EAG response to trans-2-hexenal, and their maximum EAG relative response to high concentration trans-2-hexenal was 250% and 260%, respectively. No obvious EAG responses were observed to the cedrene and cedrol from cowpea Vigna unguiculata floral. Both the male and the female moths showed clear EAG responses to sex pheromone, and significant difference was detected between males and females. The maximum EAG relative response of the males to (E10, E12)-16 CHO, a main component of sex pheromone, was 250%, while that of the females was only 53%. The difference in the EAG responses between the males and females reflected the difference in the structure, function and behavior of the males and females olfactory system.