Abstract: This study was conducted to explore a new method for determining the content of neutral detergent fiber (NDF) in forage.Single herbage,mixed herbage and silage in Inner Mongolia were selected as experimental materials,and the traditional Van Soest method was used as the control (NDF method).High temperature-resistant alpha-amylase was added during the determination process of NDF content in forage,and an additional ashing step (aNDFom method) was also included.The differences in NDF content of varied herbage samples determined by the two separate methods were statistically compared.The results showed that there was no significant difference in the contents of NDF and aNDFom among different forages (P>0.05),but the values of aNDFom were lower than those of NDF,and the content of ash in all of the tested forage samples was higher than 1%.In conclusion,it can be seen that aNDFom (NDF value reported by amylase and sodium sulfate for ash-free treatment) has higher accuracy and is more suitable for the determination of NDF content in forage.