In some foreign countries, as a mature industry, private investigation service industry has widely existed, and the number of employees is also considerable, which has played a positive role in its own social stability and economic development. Different from foreign countries, China's private investigation service has not been recognized by law. It has been in a gray area for a long time, and the professional quality of employees is uneven. On the one hand, the private investigation industry is mixed, and some swindlers disguise as private investigators to defraud customers' money; On the other hand, private investigators often violate the legal red line, and their investigation methods do not comply with the legal provisions and infringe on citizens' privacy. The reason for this situation is the conflict between the objective reality of private investigation services and the lagging legal system.

        The existence of private investigation service industry may have a negative impact on the country's criminal investigation right and citizens' right to privacy, but these are limited by the lack of complete legal norms. Just because China's investigation service industry is currently in the gray area of law, in order to pursue economic interests, its illegal and criminal phenomena emerge one after another. Its practice abroad shows that the private investigation service industry has carried out relevant services in accordance with legal norms, which has played a positive role in safeguarding foreign personal rights and interests and solving judicial problems. According to the relevant legal principles such as private relief, combined with the domestic social reality, China should recognize the legalization of the industry, strengthen the supervision of the industry, clarify its right boundary, and make it provide services under the legal framework, so as to better meet the actual needs.