Pine wood nematode ( Bursaphelenchus xylophi-lus ), one of the most destructive invasive species, has caused extremely serious economic, ecological and social losses in many countries throughout the world. Since the high repro-ductive rate of B. xylophilus PWN is the main cause of rapid death of its pine hosts ( Pinus spp.), understanding the repro-ductive and population biology and the ecology of this nma-tode are of great importance. This study mainly focused on analyzing the mating process and population structure under different combinations of sex ratios for mating. Reproductive efficiency of B. xylophilus peaked when the sex ratio (female to male) was 3.4:1. Phases of the mating process for the dif-ferent sex-ratio combinations indicated that B. xylophilus had evolved alternative reproductive strategies to cope with complex copulating conditions to obtain a suitable popula-tion structure for further propagation. This research provides fundamental information on the mechanism that is responsi-ble for the rapid population growth of B. xylophilus .