Abstract: In this paper, we studied seed dormant reasons of Hovenia acerba Lindl. based on the observations on the structure and permeability of seed coat and the seed embryo growth. In order to find out an effective way to overcome seed dormancy, the seeds were treated by cold stratification at 3-5 ℃, acid scarification, and mechanical scarification. The results showed that the low seed coat permeability was the main reasons of seed dormancy, and which was a type of physical dormancy(PY). 72% seeds germinated when exposure to cold stratification at 3-5 ℃ for 75 days, and 76% seeds germinated when exposure to cold stratification for 90 days and germinated more quickly. Soaking with sulfuric acid for 5 to 25 minutes promoted seed germination rate to 76%-81%. There were no obvious differences in germination rate among these ways of breaking the dormancy. However,there was a significant seed damage when exposure to acid scarification over 30 minutes, because the seed germination rate was only 64%. The seed started to sprout at the 4th day after parts of seed coat were removed, the germination rate reached to over 80%, this germination speed was the same as that of treating with cold stratification for 90 days. On the other hand, when the surface of seeds bruised, the seeds started to sprout on the 6th day and the germination rate was 73%.