Abstract: The present longitudinal study assessed and compared children's inhibition stability from two years to four years of age and examined the gender difference on development. Ss were from longitudinal sample in Beijing, China, 124 toddlers (2-year-old) and 103 Children (4-year-old), 21 children at 4 years dropped out because of moving, stopping cooperation, and other reasons. The study sample was children who both participated in the 2 year and 4 year observation. Children’s behavioral inhibition was rated from the Strange Situation at 2 and 4 years. Results showed that individual differences of behavioral inhibition were stable over the 2 years of the study (0.294). Compared to non-extreme group, the preservation of extreme children’s behaviors was more stable. There was no significant sex difference between boys and girls（t= -1.776, p=0.079）, but the result suggested that boys may keep uninhibited developmental trend and girls may keep inhibited developmental trend

Key words: behavioral inhibition, extreme group, non-extreme group, and stability