Based on ground penetrating radar practice on one gritty soil trough under different water disposals, the paper analyzed the variations of radar waveform characteristics. The results showed: using 500 MHz centre frequency antenna, we could get morphological characteristics and location of the dielectric anomaly object with well resolution in 1 m gritty soil pedon under different water treatments; the increase of soil moisture could decrease reflecting wave strength of the objects, lengthen two way travel time of the objects’ reflecting wave, and accordingly influence ground penetrating radargram; ground penetrating radar could accurately detect the location and depth of uncharted object through time-depth conversion on the precondition of radar wave velocity accurately obtained under homogeneous soil texture and moisture.