Archives preservation is generally divided into three types: permanent, long-term and short-term. Permanent preservation means keeping it indefinitely for as long as possible. Long-term preservation generally means that files must be preserved for about 16 to 50 years; Short-term preservation generally refers to less than fifteen years. The latter two are called regular preservation. The calculation method of regular preservation generally starts from the second year after the file is generated, and some special files and special files can be counted from the date of their invalidation and closing. All documents determined to be kept regularly must be reviewed after the expiration of the preservation period. If it is found that it needs to be retained, it should be retained, some should be retained for a long time, and some should be retained permanently. The specific situation shall be subject to the detailed provisions of the local archives department.