The principle of prohibition of improper connection is a fundamental principle in administrative law.The principle of prohibition of improper connection has profound historical logic,which is embodied in the abandonment of the system of collective punishment and the breaking away from the historical inertia of the thought of collective punishment.It has scientific theoretical logic,which is embodied in the requirements of the spirit of the rule of law and the defense of universal justice.It has a distinct practical logic,which is reflected in the need to clarify the multiple instruments of public administration.The principle of prohibition of improper connection is derived from the principle of law-based administration,the principle of proportionality and the principle of equality.However,in the group of basic principles of administrative law,the principle of prohibition of improper connection still has its unique value,especially in terms of the distinction in the application between it and the principle of legal reservation,the principle of appropriateness and the principle of prohibition of arbitrariness,which all have similar meanings.In the context of accelerating the construction of China's independent knowledge system of administrative law,the principle of prohibition of improper connection must adhere to integrity and innovation,further clarify the connotation and extension of the principle,refine the classification of improper connection,clarify the determination of improper connection,and standardize the review of improper connection.