The wood property and production process affect quality of Guqin. At the same time, Guqin shape with cavity layout relations to the improvement of Guqin technology and inheritance, so it's very important to get the internal cavity characteristics and parameters on the condition of non-destructive the structure of Guqin. The image of interior structure in Guqin was investigated by overall scanning based on non-destructive testing technology of computed tomography, which texture of faceplate, connection method between faceplate and soleplate and interior defects were studied. The three-dimensional reconstruction of Guqin cavity was achieved through Mimics software of surface rendering method and put the two-dimensional CT tomography images convert into three-dimensional, which more complete show interior structural form in Guqin, and finally the parameter of cavity dimensions was obtained. Experimental research shows that there is significant difference in Guqin interior structure between Zhong-ni and Luo-xia type, in which the fluctuation of the interior surfacein Zhong-ni type's is larger than that in Luo-xia type; the interior volume of Zhong-ni typeis less than that of Luo-xia type, especially in Guqin neck. The accurate internal information of Guqin obtained through the computed tomography (CT) technology will provide technical support for the Guqin manufacture craft and the quality examination, as well as provide the reference in the aspect of non-destructive testing for other traditional precious internal structure research.