In order to study the influence of adjacent spectral lines under positive pressure in the gas detection process of tunable diode laser absorption spectroscopy (TDLAS) technology, a pressure measurement model based on integral absorbance was established. Taking CO₂ as the research object, the simulations and experiments of pressure measurement in the range of (1~2) atm were carried out at room temperature and high purity. The results show that as the pressure increases, the degree of mutual influence between adjacent absorption spectral lines increases, and the degree of deviation of the absorbance curve from the zero baseline increases. The pressure measurement results have a maximum relative deviation of 4.94% at 1.25 atm, a minimum relative deviation of 0.73% at 2.00 atm, and an average relative deviation of 3%.