MODIS Precipitable Water Vapor (PWV) has high spatial resolution but is easily affected by environmental factors such as clouds and rain,and its accuracy is not high.GNSS PWV has low spatial resolution but has advantages of all-weather,weather-free,and high accuracy.Previous researches have shown a significant linear correlation between the two.Combining the advantages of both,correcting MODIS PWV based on GNSS PWV data can obtain PWV for large area with high precision.Yet traditional linear regression correction model does not take into account the deterioration of the linear correlation due to influences from environmental factors such as clouds and aerosols.To address this,a non-linear term of Day of Year is added to traditional linear model thus construct a new correction model.The GNSS tropospheric delay and MODIS near-infrared data in Hong Kong during 2017-2019 are used to verify the proposed correction model,and the result of linear residual spectrum shows a significant annual cycle.Compared with traditional correction model,the new model is significantly improved in aspects of average absolute error,average relative error,root mean square error,and fitting,which verifies the new model in feasibility and accuracy for MODIS PWV correction.