Abstract: Wild Aconitum sinomontanum plants growing in Yongdeng county, Gansu were marked with labels at the beginning of the blossom stage to explore their blossoming-fruiting habit and seed filling pattern. The blossoming-fruiting dynamic and the seed filling characteristics were studied by measuring the flowers, follicles, seed shape and size of the plants once every three days to provide a scientific basis for the seed development pattern and best harvest time. The buds in the wild plants gradually opened from base to top in the main anthotaxys. The flowers fruited after 3 days and the seed shape appeared in the fruit 15 days after blossom, and then the grain began to dehydrate and dry matter accumulated. The flowers developed to follicular fruits without shattering, but only the middle and basal fruits in the anthotaxys had plump seeds. In the seed filling process, the change of 100-seed fresh and dry weights all showed an “S” shaped curve which fitted to a Logistic equation. The maximum rate of increase appeared on the 14th day following blossom for the seed fresh weight and the 23rd day for the seed dry matter accumulation. The seed fresh weight increased rapidly from 7 d to 21 d and reached the highest value on the 27th day after blossom, whereas the grain dry weight increased rapidly from 16 d to 30 d. The follicular fruits fell off after 36 d following blossom resulting in interruption of the filling and the dehydration process to 50% water content in the seeds, which probably led to the deep dormancy characteristics during fast dehydration. The best harvest time for the seeds should be approximately 36 d following blossom (from the middle to the end of August) during which time the follicular fruits are not dissilient and the seeds should be harvested in timely installments.