During the work of GNSS (Global navigation satellite system) controlled land leveling system, the GNSS location data is not only the basis of topographic survey and land leveling datum design, but also affects the accuracy of land leveling in real time. In the land leveling work, if the GNSS location data is not accurate enough, the results of the terrain measurement can not truly reflect the actual terrain data and affect the entire farmland land leveling process. In order to analyze the GNSS location data error and improve the location accuracy, we proposed a method to analyze the error source of GNSS location data in the process of land leveling work. Combining the multi-path effect and random noise in the process of GNSS location data, we proposed an error correction method of vibration error caused by terrain fluctuation in land leveling work. We use the Kalman filter algorithm and Wavelet transform to process the location date and correct the data error, we can improve the positioning accuracy. We do farmland comparison experiments, and the analysis results showed that, in this method, the height location accuracy increased, during the land leveling work the GNSS positioning actual height fluctuation error range reduced by 20%, so we can use the method to guide land leveling work better, and can give the follow-up research scientific and rational positioning data, provide reliable data support.