As ground gamma spectrometry can only detect the shallow part, overburden layer will affect the value of survey in a certain degree. This paper discussed the problem of shallow overburden layer affecting ground gamma-spectrometry during geological mapping in Daxin’anling area. By sampling the radioactive elements, and analyzing the minerals in rock-soil as well as the field measure profiles, a few influence factors in gamma spectrometry application were obtained, and some basis and evidences for geological mapping have provided.