Abstract: The reproductive capacity is the symbol of population rise and fall. Evaluating plants' reproductive capacity is helpful in understanding the plants' reproductive characteristics and reproductive mechanism,and inferring the adaptive ability of plants in the environment. In full bloom,the determination was made on Bombus trifasciatus Smith's pollination efficiency-the main pollinator of Impatiens oxyanthera Hook. F.,the result showed that the amount of pollen taken out by Bombus trifasciatus Smith from stamen was far more than the pollwn fallen on the stigma,and the numlaer of pollen fallen on the stigma was far more than that in ovule,thus showing that the number of pollen on the stigma was sufficient. Artificial supplementary pollination experiments showed that the seed setting rate of cross-pollination and natural pollination was significantly different. The former improved the seed setting rate by about 11%,and homologous-pollination was not significant as compared with natural pollination. The result showed that under the condition of natural pollination,the number of fallen pollen on the stigma was sufficient,therefore,the pollen quality,rather than the quantity,was an important factor leading to a low seed setting rate of I. oxyanthera.