The synchrotron radiation computed tomography (SR-CT) technique has been applied in the research of sintering in recent years. Using this technique, the non-destructive in situ investigation of the microstructure evolution can be realized. Here the advantage of the SR-CT technique is fully developed to carry out the mechanism analysis of solid state sintering. Experiment result was quantitatively analyzed by using 3D digital image analysis technique. The method of extracting the key sintering parameters is expounded. The sintering characteristics (grain size, sintering neck, porosity, sphericity of pore) at different sintering time are calculated in the circumstances with and without sintering aids. On the basic of the SR-CT experiment result, a comprehensive mechanism analysis of the solid sintering process is carried out combining with the classic sintering theory. The successful analysis indicates that the SR-CT technique can provide a more reliable experiment result suitable for the mechanism research of sintering.