UAV（Unmanned Aerial Vehicle） with hyperspectrometer is widely used monitoring water quality in remote sensing of environment due to lightweight， flexible， low-cost， and abundant spectral information. But it is different from the satellite monitoring system， sky scattered light has a non-negligible impact on acquisition of remote sensing reflectance by UAV hyperspectral. Our research will conduct a discussion on this issue.Lake Chaohu and seven rivers around the lake are selected as the study area. The study used hyperspectral image of UAV and ASD HandHeld2 to measure the spectral signal of water， reference panel and sky light to research on the influence of sky scattered light on the remote sensing reflectance of water. Using optimized reflectance calculation method predicting SPM concentration.The result shows that the MAPD is 11.00% at a zenith angle of 45°and 17.21% at a zenith angle of 0° by substracting different sky scattered light. The result of SPM retrieval indicates that the hyperspectral reflectance subtracting 0°sky scattered light has a lower RMSE and MAPE between measured value and predicted value，8.89 mg/L and 19.60% respectively.Obviously， different angles of sky scattered light have effects on the hyperspectral reflectance of UAV.Above result shows that model of hyperspectral reflectance subtracting 0° sky scattered light has a better performance to predicting SPM. We should subtract 0° sky light hyperspectral to calculate reflectance when predicting water quality parameters based on UAV.