The invention discloses an air pressure data acquisition module as well as a differential barometric leveling system and method, belonging to the field of navigational positioning and communication. The method involves a structure of the air pressure data acquisition module, and comprises the following steps: collecting air pressure data and correcting; storing and displaying the collected air pressure data, and waiting for communication processing; judging whether the collected data is abnormal or not; waiting for instruction frame information sent by a channel unit, and forming communicationinteraction between a microprocessor and the channel unit; performing peripheral packaging processing on the air pressure data acquisition module by using a packaging box. A high-precision measurement function of the differential barometric leveling system can be supported well, and high use value is achieved during height measurement in technical fields such as ground exploration and meteorology.