Abstract: During classified flowering period of nine excellent pecan(Carya illinoinensis)cultivars, flower morphological characteristics, pollen viability and stigma receptivity were measured by taking digital photos, in vitro germination method and benzidine-H₂O₂testing. The results showed that optimal period for pollens collection was “stage Ⅴ” when the angle between bracts and catkin rachises were about 90° and anthers turned yellow. Among the tested cultivars, ‘Pawnee’ had the highest pollen viability. For the pollen collection, some cultivars like ‘Mahan’ was collected more easily when the open angles of stigmas from 90° turned to more than 90°, other cultivars like “Pawnee” had receptivity from the beginning when stigmas started open and got better when open angles got bigger from 15° to 90°, which were relatively smaller than the fomer. The optimal receptivity time for all cultivars were only lasted 2-3 days. Receptivity would lost when black spots appeared on the stigmas. Pollen spreading time of ‘Pawnee’ overlaid with best stigma receptivity time of ‘Mahan’, and the pollination time of ‘Pawnee’ and ‘Mahan’ was longer than others, so they were suggested to be optimal pollination cultivars.