Abstract: ObjectiveThe present experiment was conducted to reveal molecular mechanism of recognition of sex pheromone by studying key amino acid residues and interaction force types among sex pheromone binding protein , recep-tor protein and sex pheromone of Plutella xylostella, in order to provide new ideas for development of new sex lures and harmless control of Plutella xylostella. MethodThe binding mode and interactions between Z9-14∶AC and any of PxylPBP2 and PxylOR4 were analyzed through the molecular docking with LibDock module and the free energy calculation with Cal-culate Energy module of Discovery Studio 2.5 software. ResultThr9 was responsible for the formation of hydrogen bond between Z9-14∶AC and PxylPBP2. Besides, Z9-14∶AC tended to produce hydrophobic interaction with Leu residues. The main driving force of the docking between Z9-14∶AC and PxylPBP2 was electrostatic energy, while the main driving force of the docking between Z9-14∶AC and PxylOR4 was van der Waals energy, but the binding of Z9-14∶AC and PxylPBP2 as well as Z9-14∶AC and PxylOR4 were suppressed by solvation energy. ConclusionThere are significant differences in the recognition and combination of sex pheromone molecules between the sex pheromone receptor protein , and sex pheromone binding protein in diamondback moth, as the former protein responds to sex pheromone more sensitively, and the compound is more stable.