Abstract: The abnormal bloom of marine organisms in the sea area around the water cooling system of the nuclear power plant can lead to the blockage of the water intake, which affects the normal operation of nuclear power seriously.Our study carried out laboratory experiments and field experiments using Siganus guttatus as the experimental object.We studied the feeding of the fish on the dominant algae Ulva linza under different temperature gradients (29℃, 26℃, 23℃, 20℃ and 17℃) in the laboratorial simulant experiment and the feeding on Ulva linza and Ulva pertusa in situ.We found that Siganus guttatus had the strong ability of feeding Ulva linza in laboratory experiments.In the suitable survival temperature range, the higher temperature resulted into the higher feeding rate.In the 29℃ group, the average feeding rate was as high as 7.86%.In field experiments, it was found that Siganus guttatus grew well and had high preference to Ulva linza and Ulva pertusa.In summary, Siganus guttatus has the potential to prevent the algae boom in the sea area around the water cooling system of the nuclear power plant.However, specific measures and ecological risk assessment need further discussion.This study provided the theoretical basis and the technical support for the prevention.