At present, there are some defects such as subjective randomness, large threshold value and unstable threshold solution in the existing decision-making and evaluation laboratory. To solve the above problems, the DEMATEL threshold determination based on Tsallis relative entropy is proposed. Firstly, based on the quality control theory, the expert score table is screened. Then the evidence theory is used to fuse the expert opinions, the most important influencing factors are selected from the influence relationship, and the influence relationship is taken as the upper limit of the threshold. Finally, the interval pair matrix element is applied. The probability distribution of the information is defined, and the segmentation threshold corresponding to the minimum relative entropy of Tsallis is selected as the final threshold. Comparing with other methods, the threshold determination method based on Tsallis relative entropy can effectively remove the redundant information in the system, and it is more general in use. The example calculation also verifies the operability of the whole threshold determination process.