Abstract: Marine enclosure experimental technologies for thermal discharge effecting on ecosystems was a ground-breaking study. So three enclosure ecosystems experiments placed in explicit warming water area, weak warming water area and natural temperature water area around Xiangshan Port power plant on July, 2011 and the repeated measurement data analysis method, mixed effects linear model, were being introduced here. Accordingly, the study was conducted in order to analyze the possible impact factors on phytoplankton growth, identify the controlling factors and interactions, and establish the response relationship between these factors and phytoplankton abundance. Finally, the rationality of the temperature zone setting can be discussed. The study can be one of technical guidelines about thermal discharge effects on environment and provide technical support for formulating technical standards and methods of thermal discharge effect research. It can also be used in estimating ecological compensation of thermal discharge damage and so on.