Public security admonition is an admonition measure similar to criticism and education, which is carried out for minor offences that are not serious enough to be punished according to the Public Security Administration Punishment Law. Its function and purpose are similar to the "warning" in administrative punishment, but there is no relief channel. These realistic contradictions provide space for abusing public security admonition. Whether the admonition is an administrative punishment depends not only on its external manifestation, but also on its content, legal basis and purpose. In addition, whether the public security admonition is an administrative punishment measure and whether it belongs to the scope of administrative cases should be analyzed through case study. One important factor is whether the contents in the admonition have actual influence on the rights and obligations of the administrative counterpart.