In this paper,air pressure is precisely measured based on water vapor broadening linewidths using tunable diode laser absorption spectroscopy (TDLAS) technology. In order to get comprehensive data of the absorption spectroscopy,the laser beam is sput int o two parts in the experiments.One of the laser beam passes through the measurement cell for the absorption spectroscopy,while the other passes through the FP etalon for calibration.Two ab sorption lines near 7243cm－1 are chosen for measureme nt.Before the experiment,the air broadening line coefficients of the two absorption lines in the HITRAN database are calibrated b y measuring the linewidths from 10kPa to 20kPa.As the reference pressure varies fr om 30kPa to 100kPa in the experiment,the deviations of the measure d pressures based on the absorption lines at 7243.07526cm－1 and 7 242.37075cm－1 are about 0.9% and 2.0%,respect ively.The fluctuations of the measured results based on two absorption lines are both less than 0.2%.The m easured results from experiments,which differ little under the same conditions,are almost the same with reference pressures.The experimental results demonstrate that precise measuremen t of air pressure using TDLAS technology is feasible.As a result,this technology will b e applied widely in environmental monitoring as well as in the field of flow dia gnosis.