The experiment was conducted to investigate the effects of different levels of Optigen, a new slow-release non-protein product, on milk performance and plasma biochemical indices of Xinong Saanen dairy goat, thus to select the optimum supplemental level in the diet. Forty-eight healthy lactating Xinong Saanen dairy goats with average BW of 60 ± 8.98 kg were assigned to 4 groups with 12 goats in each group. Goats in the 4 groups were fed experimental diets containing 0, 0.25, 0.5, or 0.75% Optigen, respectively. There was a pretrial period of 1 wk followed by an experimental period of 16 wk. The results showed that (1) the dietary Optigen level did not significantly affect average daily feed intake (P > 0.05); (2) goats in the group with dietary Optigen level of 0.5% have a significantly high average daily milk yield (P < 0.05); (3) the dietary Optigen level had significant influences on milk fat (P < 0.05), but there was no significant difference among 3 experimental group containing 0.25, 0.5, and 0.75% Optigen in the diet (P > 0.05); milk protein percentage, milk lactose percentage and SNF percentage were all unaffected (P > 0.05) by the supplementation of Optigen; (4) the dietary Optigen level had significant influences on plasma urea nitrogen (P < 0.05), goats with 0.5% Optigen supplement in the diet demonstrated the lowest plasma urea nitrogen content, and followed by that with 0.75% and 0.25% Optigen supplement in the diet. Plasma triglyceride, total cholesterol and total protein were unaffected (P > 0.05) by the supplementation of Optigen. In conclusion, dietary supplementation of Optigen can increase milk fat content and reduce plasma urea nitrogen content. 0.5% supplementation of Optigen in the diet can obtain a higher fat content and milk production.