Extracts from lo-han-kuo (Siraitia grosvenorii) are of high sweetness and low calories, and they have been widely used as a natural sweetener to reduce the risk of obesity and diabetes. In the current study, lo-han-kuo extracts were extracted using subcritical water under different operation condition. The study revealed that the optimal extracting parameters were: extraction time of 20 min, extraction temperature of 140 degrees C, and the addition of 15% ethanol. Antioxidant activity, contents of total flavonoids, and total phenolic compounds of lo-han-kuo extracts were also investigated. A mathematical model was established to describe the relationship between antioxidant capacity and content of bioactive components in lo-han-kuo extract, and it was found that antioxidant capacity of the extracts was mainly attributed to the yields of total mogrosides (P<0.05).