In order to better study the variation of water quality in Lake Hongfeng, the changing trend of nutrient and chlorophyll-a concentration was analyzed, and the water nutritional status was evaluated by water trophic level index (TLI) method based on monthly sampling monitoring data of 7 representative monitoring sites of Lake Hongfeng from 2009 to 2018 by environmental protection monitoring station of two lakes and one reservoir in Guiyang Province. Besides, the correlation between TLI and water chemical composition (total phosphorus, total nitrogen, etc.) and hydrometeorological conditions (water level, temperature, etc.) was statistically analyzed by Pearson. The results showed that the monthly concentration of total nitrogen in the water body fluctuated significantly (ranging from 0.56 mg/L to 2.80 mg/L), and the concentration in spring and summer was higher than that in autumn and winter. The monthly concentration of total phosphorus (from 0.016 mg/L to 0.103 mg/L) in summer was slightly higher than that in winter, and monthly ammonia nitrogen (from 0.007 mg/L to 0.710 mg/L) was spring > winter > autumn > summer, The monthly concentration of chlorophyll-a fluctuated seasonally from 0.8 mg/m³ to 38.9 mg/m³, summer > spring > autumn > winter, and the inter-annual trend was first increased and then decreased. The concentration of total phosphorus, ammonia nitrogen and chlorophyll-a decreased on the whole, which suggests the water quality is improving greatly during the past ten years. Lake Hongfeng was in the state of medium nutrition to the mild eutrophication state in the past ten years, and the TLI showed a trend of decline year by year. TLI in summer was significantly higher than that in other seasons. Statistical analysis showed that the chlorophyll-a concentration in Lake Hongfeng was significantly positively correlated with ammonia nitrogen, total phosphorus and potassium permanganate index, while negatively correlated with the nitrogen-phosphorus ratio. The chlorophyll-a concentration was also significantly positively correlated with water temperature, pH, rainfall, air temperature, and sunshine, and negatively correlated with transparency and air pressure, it was not significant correlation with water level, humidity, and wind speed. The results suggest that chlorophyll-a concentration in the reservoir ecosystem is not only controlled by nutrient concentration, but also controlled by meteorological and hydrological conditions.