Abstract: In 1996,a field survey was conducted to investigate the giant panda population in Huanglongsi Nature Reserve and cluster analysis method was used to analyse its age structure.The results showed that there were 23 pandas in the reserve and the ecological density in bamboo forests was 0.439 giant pandas/km2.The population could be divided into four age groups with the Sum of Square Method.The cub group accounted for 13.33%,the juvenile group for 6.67%,the adult group for 60%,and the senile group for 20%.This determination was almost in accordance with the principle proposed by Hu (1987),and at the same time it indicated that this population had a stable tendency.However,it was such a small population that a little interrupt could lead it to extinct.Thus,at present it is urgent to protect the habitat and the corridors and ban the mining in the area.