Amaranthus palmeri is a dioecious invasive weed, which poses a great threat to agricultural production and biodiversity protection in China. Although many studies have explored the invasiveness of invasive alien plant species from the perspective of resource utilization efficiency, surprisingly few studies have investigated the sex-related traits in invasive alien plant species. In our study, four different types of A. palmeri were selected to investigated the leaf morphology, allometric growth patterns and ecological stoichiometry of carbon (C), nitrogen (N) and phosphorus (P) between male and female, which typical invaded regions in Jizhou District (JZ), Baodi District (BD), Xiqing District (XQ) and Jinghai District (JH) in Tianjin. Results demonstrated that the leaf width (LW), leaf length (LL), leaf area (LA) and specific leaf area (SLA) of the male plant were generally significantly higher than those of the female plants. Compared with the female plants, the straits of the male plants were closely sex-related and had an allometric growth relationship. The leaf N content (N_mass) and P content (P_mass) of A. palmeri were higher than the average of Chinese terrestrial plants, while the leaf carbon-nitrogen ratio (C/N) and carbon-phosphorus ratio (C/P) of A. palmeri were lower than the average of global terrestrial plants. It is concluded that A. palmeri may have different ecological response strategies, which can adapt to the habitats to achieve a successful invasion by optimizing the resource allocation and utilization efficiency between male and female plants.