Ground penetrating radar (GPR) is an effective tool to detect buried targets, which detects buried targets via the discontinuity of dielectric. Ground penetrating radar has a lot of virtues, such as rapid and continuous surveying, simple and convenient operation, high resolution, nondestructive detection etc, so which has been used to fields of national defence, police, construction of highway, railway, bridge, tunnel, and prospecting, geologic studies, archaeological studies etc.There are more and more researches on ground penetrating radar technology with the applications of GPR increasing. The international conference on ground penetrating radar being hold every two years in recent years, a lot of papers about GPR technology have been published in all kinds of academic magazines. The applications of GPR can be sorted shallow, middle and deep depth three classes according to depth of targets, these applications belong to shallow depth, such as detecting landmines, unexplored ordnances, reinforcing steel bar, inspecting quality of freeway, etc. The research on GPR for middle and deep depth applications are comparatively mature. The demand for GPR in detecting shallow subsurface targets is very high, it is very necessary to research on signal processing of GPR for improving performance of GPR.This paper studied signal processing technology of GPR, included clutter reduction, synthetic aperture imaging, automatic target detection, target identification, etc. The contents and innovations of this paper are as follows:1. Discussed some methods of clutter reduction, introduced the mean-removed background method in detail. Proposed two new methods of clutter reduction, one is extremum point location based on signal characteristic of step frequency ground penetrating radar, this method is available to step frequency ground penetrating radar only, the other reduces clutter based on image processing technology, this method is very effective and universally valid.