Abstract: This study aimed to assess the ecological value of CO2 fixating and O2 releasing by ecosystem of natural grassland in the surrounding area of Qinghai Lake. Taking the natural grassland in Gonghe County of Qinghai Province as an example, the ecological value of CO2 fixating and O2 releasing were calculated. The results showed that the net growth production of dry matter of the grassland in study area was 1 196 147.15 t per year; the total CO2 fixating and O2 releasing were 1 949 719.86 t per year and1 435 376.59 t per year, respectively, and the ecological value of them was 9.018 722×108Yuan per year and 5.403 691×10^8Yuan per year, respectively. It is suggested that great importance should be attached to the protection of natural grassland ecosystem when the animal husbandry economy are developing.