Kapok trees (Bombax ceiba) grow well and have normal flowering and seeding capacity in Hong-He dry-hot valley (DHV), which is characterized by a dry and hot climate. The valley sees small rainfall and long duration of drought during the dry season. Kapok seeds have a normal germination potential, but their natural regeneration is very poor. Young trees or seedlings are seldom observed under a mature kapok tree. The causes of the difficulties with their natural regeneration and the related factors controlling the regeneration process remain unclear. To understand the process of seedling development and the causes of problems with natural regeneration, we measured seed production per tree, seed dispersal characteristics as well as the field and indoor seed germination potential in a kapok natural population in Hong-He DHV. The results showed that each mature kapok tree produced (98092±2540) seeds on average. The mean fruit number per tree and the mean seed number per fruit were 358 ± 46 and 274 ± 45, respectively. These findings indicated that the seed source was abundant. The seeds started to disperse by flying with kapok fiber after the fruit cracking from late April to early May. Most of the seeds (82.7%) dispersed within the distance 4-22 m around the parent tree. The area 14 m away from the parent tree was the concentrated seed dispersal zone, with seed density 1005 seeds/m². The seed rain lasted for 15 days. The losses among the seeds falling on the ground were high. Approximately 30.2% of these seeds were taken by birds, ants, and mice, and 54.0% of the seeds perished because of mildew. Field germination tests showed that the germination rate for the treatment with 2 cm surface soil mulching was 60.3%, whereas the germination rate for the treatment without soil mulching ranged from 15.0% to 38.8%. The seeds did not germinate if the soil mulching depth was 6 cm. Apparently, the seeds falling onto the bare land without soil mulching or with excessively deep soil mulching have low germination rates. Additionally, the sterilization test with different disinfection treatments demonstrated that an infection reduced the germination rate by 40.8%. The seed viability was also influenced by seed moisture conditions. The seed moisture decreased with the increasing period after seed falling up to 40 days. Seeds at 10-35 days after maturation had moisture content of 2.1%-5.9% and showed the best seed viability, but the viability declined significantly 45 days after maturation. Soil moisture of 20%-40% was favorable for seedling development. This result indicated that both seed and soil moisture directly affected seed germination and the seedling development process. The seeds showed a wide span of tolerance to temperature changes. The seeds could germinate at a temperature between 10 and 50 ℃, showing the best germination rate at 30-35 ℃. In conclusion, weak precipitation and prolonged drought during the dry season in these dry-hot valleys lead to conditions that are inhospitable to germination and growth. These conditions reduce the number of remaining seeds, lower soil moisture content, and shorten the seed viability period. Therefore, weak rainfall and a long drought seem to be the bottleneck that restricts the progression from seedlings to young trees. Soil mulching (1-2 cm) can increase the seed germination rate by improving moisture conditions.