Effects of roasting temperature and duration on the composition fatty acid and pigment and antioxidant attribute of Chlorella pyrenoidosa were studied. The results showed that oleic acid (C_18:2) and linolenic acid (C_18∶3,n3) were the predominant fatty acids species, and poly unsaturated fatty acid (PUFA) accounted for ca. 76.69% of total fatty acids in Chlorella. Roasting treatment had little effect on fatty acid content and composition when the temperature no higher than 150 ℃. However, remarkably decrease of PUFA content was found with 200 ℃. Both pigments and the antioxidant activity of ethanol extracts (scavenging DPPH) from C.pyrenoidosa were sensitive to roasting temperature. Obviously degradation of chlorophyll and carotenoids were found when roasting temperature was higher than 100 ℃, while the antioxidant activity of ethanol extracts from chlorella decreased dramatically with roasting treatment over 150 ℃.