Abstract: To study the alleopathic inhibition frequency and stability of allelopathic rice to bamyardgrass under different field environments, 3 conventional allelopathic rice varieties, 7 hybrid rice combinations of the three conventional allelopathic rice with three CMS lines and PI312777, an excellent American allelopath rice were planted in the paddy filed at different time. The results were as follows: rice varieties and environment had significant influence on the alleopathic inhibition frequency while their interaction showed no significant difference. The higher the alleopathic inhibition frequency of the rice or the environment was, the more stability its inhibition frequency was. That meant the rice variety which had a highly alleopathic inhibition frequency showed little difference in different environment, while different alleopathic rice showed little difference in the highly alleopathic inbibition environment. By using the conventional alleopathic inhibition rice as donor parents, the allelopath heterosis was easily obtained in F1. In some period of time after the rice plants were transplanted for 0 to 15 days, the average temperature, the lowest and highest daily temperature as well as the sunshine duration had effects on the alleopathic inbihition. The lower the temperature and the shorter the sunshine duration was, the higher the alleopathic inbihition frequency would be. Besides the climate environment showed diversity impact on alleopathic inbihition, there might be other more important factors affecting the alleopathic inhibition frequency. The results showed that allelopathic inhibition frequency stability of allelopathic rice was easily affected by the environment in the field, which was unfavorable for production applications, but could be used to select high and stable allelopathic inhibition frequency of allelopathic rice.