Take part in public security work. According to Article 6 of the Notice of the Ministry of Public Security on Rewarding Retired Cadres of Public Security Organs, the length of police service is calculated from the date of participating in public security work. The length of service should be calculated from the date of joining the work. According to Article 16 of the Ministry of Public Security's Answers to Some Specific Questions about the First Assessment of Awarding Police Ranks, graduates from public security colleges and local colleges and universities cannot calculate their length of service when studying at school. Considering the needs of knowledge and specialization of the people's police force is conducive to attracting talents and improving the quality of the people's police force. When the police rank is awarded for the first time, the study time in full-time police colleges and local colleges can be included in the working years according to the prescribed academic system.