Taking Yanghe Reservoir for example,the paper colected reservoir water samples and sediment samples and analyzed the water quality in reservoir. Based on AGP-experiment, it studied the relationship between the growth of advantage algae in reservoir and the factors such as temperature, light, nutrients. The study showed that the optimum growth temperature of Anabaena is 24°C, the optimum growth temperature of microcystin is around 28℃, and they both grow well in bright light. The use proportion of nutrients which is from sediment leaching is obviously enhanced. The experiment results discoveered the growth impact factor of dominant species in reservoir and exactly found the reason of reservoir eutrophication. The results can provide scientific and theoretical guidance for effective forecast and control of eutrophication.