Abstract: Six Guanzhong dairy goats with permanent rumen cannula were used to determine the effects of four different ratios of NFC to NDF in diets on the ruminal pH dynamics.The NFC/NDF were1.02（Ⅰ）,1.24（Ⅱ）,1.63（Ⅲ） and 2.58（Ⅳ）,respectively.In the present study ruminal pH were monitored continuously by continous ruminal pH measuring and recording system.The results showed that①Ruminal pH values were decreased significantly with the increase of NFC/NDF.②With the increase of NFC/NDF,mean duration times for pH lower than 5.2,5.5,5.8 and 6.0 were increased from 0,0,2.42 and 9.40 h to 0.33,7.50,17.06 and 20.53 h,respectively. At the save time,curve areas for pH lower than 5.5,5.8 and 6.0 were increased from 0,0.21 and 1.43 to 1.09,4.84 and 8.59.The rate and degree of pH decline post feeding and the duration of pH nadir were increased with increase of dietary NFC/NDF.