Abstract: Rice (Oryza sativa) straw harvested at the appropriate time to achieve good nonstructural carbohydrate content (NSC) was utilized in this study; the main NSC was starch. Starch in rice straw should be initially hydrolyzed into water soluble carbohydrates (WSC) which are able to be utilized by lactic acid bacteria during the ensiling process. Two rice varieties (hybrid indica rice, variety Liangyoupeijiu and common japonica rice, variety Wuxiangjing 14) containing different NSC in the straw were treated with four different concentrations of α-amylase (0.5, 1.0 and 1.5 g/kg) to investigate the effects of α-amylase on rice straw silage quality. The results revealed that the NSC and starch content in the straw of Liangyoupeijiu was 6.89% and 3.68% respectively, significantly lower than Wuxiangjing 14 (P<0.05), 16.51% and 10.63% respectively. The forage quality and fermentation quality of rice straw resulting from different α-amylase treatments also differed significantly (P<0.05). 1.5 g/kg of α-amylase was optimum for Liangyoupeijiu whereas 1.0 g/kg α-amylase was optimum for Wuxiangjing 14. After α-amylase application (2-3 days), the NSC, WSC and starch content in the straw of Liangyoupeijiu, and the NSC and starch in the straw of Wuxiangjing 14 decreased, while the WSC in Wuxiangjing 14 increased and was significantly higher than the control. However during the 5th to 14th days of ensiling the WSC content decreased sharply and differences between α-amylase treatments were minimal.