Investigation is an activity carried out by special state organs to ensure the implementation of the law, so we must adhere to the principle of the rule of law. However, for quite some time, China scholars' research on this issue is relatively few and abstract. With the development of China's legal system construction, especially the revision of the Criminal Procedure Law and the Criminal Law, and the slogan of "ruling the country according to law" put forward by the 15th National Congress of the Communist Party of China, scholars have strengthened their research on the legalization of investigation.

From a macro point of view, some scholars have comprehensively discussed the problem of "handling cases according to law", pointing out that "the key problem of strictly enforcing the law and handling cases according to law in investigation is to strengthen the legal concept of the investigation team and improve the legal awareness, legal quality and law enforcement level"; Some scholars discuss from the perspective of "scientific case handling" that improving the scientificity of law enforcement must be based on a solid legal concept; Another scholar thinks that the change of discipline name from "reconnaissance" to "investigation" reflects the progress of legalization of investigation work in China to some extent.

From the microscopic point of view, scholars mainly study the influence of the revision of the criminal procedure law on investigation. Some scholars have discussed the difficulties and countermeasures of self-investigation and pre-trial work after the revision of the criminal procedure law, and put forward specific measures to strengthen the study of the revised criminal procedure law and rationalize the case handling system; Some scholars have analyzed the problem of handling cases according to law in specific investigation measures such as interrogation and search. Some scholars have analyzed the phenomenon of illegal evidence collection, and put forward that a set of evidence collection rules should be established in combination with China's specific judicial practice and with reference to some concepts of world litigation. Some scholars have discussed how to improve the legal awareness, legal quality, legal concept and law enforcement level of investigators. In addition, investigation and supervision is also a hot topic discussed by scholars.