Scholars have found that the main reason for the sea level pressure suspicious information of the unmanned automatic weather station is that the pressure sensor altitude setting of the observation equipment is incorrect. After the frequent correction of the sea level pressure suspicious information for conventional stations, there still exists a certain case that some conventional stations (that is, the previous regional automatic stations) have frequent sea level pressure suspicious messages. This paper presents another cause of frequent occurrence of sea level pressure suspicious information in the Meteorological Data Operational System (MDOS), which fundamentally solves the problem that the sea level pressure of some conventional stations has not passed the internal consistency check for a long time. The phenomenon provides a reliable basis for relevant stations to solve such problems, and attracts the attention of relevant observation departments.