The mechanism of reproductive behavior and sperm competition strategy in Helicoverpa armigera (Hübner) has been an interesting topic for quite some time. In the current study, sperm motility pattern and sperm competition in H. armigera were investigated. The majority of apyrene and eupyrene sperm from spermatophore were simultaneously transferred to spermatheca 2 h after copulation. During 3–24 h after copulation, the amounts of apyrene and eupyrene sperm both sharply decreased and only approximately one seventh of one ejaculate remained stable. We used highly variable microsatellite loci to survey 13 families with a total of 379 offspring (mean 29.2 per family). In 8 of 13 families, all offspring were assigned to the last male, and 85.9% of offspring were sired by the last male in total. The possible mechanism of sperm competition in H. armigera encompassed the combined effects of both relatively fixed volume of sperm storage by females and the displacement of sperm from the formerly mated males. This study provides insight into the mechanism underlying sperm precedence in H. armigera, and it is important for potential control of the cotton bollworm.