Abstract: The multipath has long been considered a major error source in GPS applications. This paper analyzes the characteristics of the GPS signal multipath effects, bases on which do an experiment that considers the characteristics of dynamic deformation monitoring. The solution results of observation data to successive two days are processed by a method, which combines the wavelet filtering and the differential correction between successive two days. The research demonstrates that the multipath errors have stronger repeatability on successive days; after significantly mitigating the influence of multipath effects, the accuracy of three-dimensional positioning for GPS dynamic deformation monitoring can attain the mm level, an obvious accuracy improving particularly in vertical component. The characteristics of GPS signal multipath, the experimental scheme and the qualitative and quantitative analysis of results are detailed.