According to the expiration period of normal service:

1. Corporal: 3 years

2. Sergeant: 3 years

3. Staff sergeant: 4 years

4. Fourth-level master sergeant: 4 years

5. Third-level master sergeant: 4 years

6. Second-level army.

According to the current legal documents, soldiers are divided into compulsory military service soldiers and voluntary military service soldiers according to the nature of military service, and the voluntary military service soldiers are called non-commissioned officers. The ranks of non-commissioned officers are as follows:

① Senior non-commissioned officers: first-class master sergeant, second-class master sergeant and third-class master sergeant.

② Middle-level non-commissioned officers: Fourth-level master sergeant and staff sergeant.

③ Junior noncommissioned officers: sergeants and corporal. Non-commissioned officers are selected from conscripts who have completed their active service, appointed from cadets who graduated from military academies, or directly recruited from citizens with professional skills in non-military departments. Non-commissioned officers must have the following basic conditions: volunteering to devote themselves to national defense, being competent for their jobs, having a junior high school education or above, being healthy and having good conduct.

The conditions for conferring and promoting the rank of noncommissioned officers are as follows:

① Junior noncommissioned officers: those who are selected as junior noncommissioned officers after the expiration of their active service are promoted to corporal; Corporal who continues to serve in active service after the expiration of three years shall be promoted to sergeant.

② Intermediate noncommissioned officers: if a sergeant is selected as an intermediate noncommissioned officer after three years of active service, he will be promoted to a staff sergeant; If a staff sergeant continues to serve in active service after the expiration of four years, he will be promoted to a fourth-grade master sergeant.

③ Senior non-commissioned officer: if the senior non-commissioned officer is selected after four years' active service, he will be promoted to the third-grade sergeant; If the third-class master sergeant continues to serve in active service after the expiration of 4 years, he will be promoted to the second-class master sergeant; If the second-class master sergeant continues to serve in active service for 4 years, he will be promoted to the first-class master sergeant. The maximum service life of non-commissioned officers is 6 years for junior non-commissioned officers, 8 years for intermediate non-commissioned officers and 14 years for senior non-commissioned officers. Junior noncommissioned officers and intermediate noncommissioned officers shall, within the maximum period of active service at the corresponding level, determine the time of active service in accordance with the post establishment regulations.