In order to effectively prevent risks from turning into hazards, it is necessary for the legislation to authorize the police to take measures to collect information. However, these measures may violate the human rights. In police law, how to legislate so that the monitoring is not excessive and human rights are not infringed, in the name of improving efficiency or safeguarding national security, has profound research value. Within the scope of police law, this article is divided into five parts. In addition to the preface, it discusses the constitutional issues of secret infiltration of computers to collect informations, the relevant judgment of the German Federal Constitutional Court and legal systems, the legal basics of police law in my country, and at last, states conclusions and recommendations.