Abstract: Based on the Kendall-Goodman model we propose a two-sex model with birth and death rates for male and female sub-populations different. If there is no density-dependent effects a positive exponential solution is deduced and the conditions for its global stability is obtained; with density-dependent effects considered, conditions for the global stability of the positive equilibrium is concluded for a fixed birth function. Consequently, we show, whether considering density-dependent effects or not, the sex ratio is stable.