Abstract: Chlorella vulgaris is a common freshwater alga. Anabaena sp. strain PCC is one of the most common blue-green alga in eutrophic lakes. To better understand the growth of water bloom blue-green alga in eutrophic lakes and the relationship between alga growth and temperature, we investigate the interspecies competition between C. vulgaris and Anabaena sp. strain PCC at different temperatures. The results showed that in both uni-culture and co-culture systems, C. vulgaris and Anabaena sp. strain PCC reached the maximum growth rates at 35℃ and 3035℃ respectively. We also found that the inhibition parameters of interspecies competition could be significantly influenced by the temperature. The maximum inhibition parameter of Anabaena sp. strain PCC against C. vulgaris, 0.9111, was observed at 15℃. This value was 1.24, 1.14, and 1.12 times higher than the parameters at 25, 30℃, and 35℃ respectively. The maximum inhibition parameter of C. vulgaris against Anabaena sp. strain PCC, 18.38, was observed at 30℃, which was 4.25, 2.03, and 1.20 times higher than those at 15℃, 25℃, and 35℃ respectively. According to the Lotka-Volterra model, we deducted that the coexistence of Anabaena sp. strain PCC and C. vulgaris was unstable in the co-culture system at these four temperatures.