To explore the effects of different dietary NFC/NDF ratios on ruminal fermentation parameters, 6 Guanzhong dairy goats with permanent ruminal cannulae were divided into 4 groups （4 trial time） and each time lasted for 10 d according to self-contrast design experiment. The goats were fed diets with different NFC/NDF ratios, which the ratios were 1.02 (period Ⅰ),1.24 (period Ⅱ),1.63 (period Ⅲ) and 2.58 (period Ⅳ), respectively. The results showed that with the increase of dietary NFC/NDF ratios, ruminal pH decreased. The rate and degree of pH decline and duration time under pH 5.2, 5.5, 5.8 and 6.0 were increased. Ruminal propionate, butyrate and TVFA content tended to increase, while ruminal acetate content and A/P ratio tended to decrease. Plasma acetate, propionate, butyrate and TVFA content tended to increase. When NFC/NDF ratio was 2.58, duration time of ruminal pH between 5.2 and 5.5 could last for more than 7 h. In this case, ruminal lactate content remained at a low level, blood and ruminal TVFA content raised significantly (P<0.05). The results indicated rumen fermentation pattern was changed with the increase of dietary NFC/NDF ratios which caused acid environment in rumen; the accumulation of TVFA content was the main reason for pH decrease but not lactate itself; when NFC/NDF ratio was 2.58, SARA occurred in dairy goats.［Chinese Journal of Animal Nutrition, 2010，22（3）:595-601］