Compared with spectral gamma-ray tool applied to exploration for oil-gas field, the design of non-oil spectral gamma-ray tool is different, which is applied to such exploration as coal field, metal ore or non-metal ore, and engineering geology, etc. This paper puts forward a method of spectral gamma-ray logging signals transmission via a long cable in form of analogue, and some experiments have been made out. The results of the experiment show that signals transmission via a long cable in form of analogue is a new method for designing spectral gamma-ray logging tool.