By taking a duo-membrane box as a sensing component for atmospheric pressure,a micrometric optical fiber displacement sensor was employed to inspect deformation of membrane box with air pressure changing to avoid the defects in inspecting deformation,or improve and optimize performances of the sensors.A channel optical fiber sensor was utilized to increase sensitivity and to measure little change in air pressure.The relation between optical fiber sensor output changes and atmospheric pressure changes was calibrated with a standard air pressure gauge.A setup for measuring atmospheric pressure was developed.The experimental results indicate that the measurement range is 900～1 170 hPa,the resolution is 0.2 hPa,and the accuracy is ±0.1 hPa.The measurement area position on air pressure can be changed via the changing of initial distance between optical detector and reflection face,and the measurement range on atmospheric pressure can be expanded via optimization of optical fiber detector parameters.