To monitor the eutrophication of Luhun Reservoir, the entropy osculating value method combined with the eutrophication evaluation criteria of lake and reservoir was applied to evaluate the nutrient status of Luhun Reservoir from 2009 to 2015. The results showed that the reservoir was in slightly eutrophication with total nitrogen exceeded the standard. There were differences between the entropy osculation method and the linear interpolation scoring method. There was more subjective without considering the impact of various indicators on the evaluation results for the linear interpolation scoring method, whereas the entropy osculation value method could reduce this subjectivity and can determine the main factors affecting the water quality, which made the evaluation results more consistent. Therefore, the entropy osculation value method can be used as a common method to evaluate water quality.