At the legislative level, China has not recognized the evidence qualification of polygraph opinion. However, as the application of lie detection in judicial practice continues to expand, polygraph opinion has been treated as evidence in some judgments. The main obstacles to the evidentialization of polygraph opinion come from two aspects: accuracy and legality. In fact, in terms of accuracy, with the development and improvement of polygraph technology, the standardization of the examination procedures and the accuracy rate of the conclusions have been continuously improved. Polygraph opinion can provide a strong guarantee for the credibility of evidence admissibility and fact-finding. In terms of legality, although the act of polygraph test itself lacks a clear legal basis, legality can be vested in it through academic interpretation. Furthermore, after obtaining the informed consent of the person being tested, choosing to accept a polygraph test implies the willingness to make certain concessions regarding basic rights such as the right to privacy. At this point, polygraph test does not constitute an infringement on the citizen’s right to privacy or the right to physical freedom. Granting the evidence competency of polygraph opinion at the legal level and incorporating it into the legal system can not only eliminate the negative impact of the unpredictability of judicial discretion but also play an active role in unifying the judiciary and achieving judicial civilization.