Use of Isochrysis galbana, Nitzschia closterium, Platymonas sp, studies of the effects of TPTC on structural variation and biosuccessive process of marine microalgae community showed that the toxicity of TPTC to them was in the order of Isochrysis galbana, Platymonas sp. and Nitzschia closteriu and that their 96 h EC50 of exponential growth coefficients were 1.32, 4.55 and 6.21 μg/L, respectively. At concentration of 0.01-lμg/L, TPTC will accelerate the decline of Isochrysis galbana while promote Nitzschia closterium to become the dominant species. TPTC at 10μg/L will break down the microalgae community.