In response to the demand for non-contact measurement of gas pressure, a technical analysis of barometric pressure measurement based on the TDLAS direct absorption method was carried out. Taking CO2 as the research object, through the theoretical study of absorption spectrum based on Beer-Lambert law, a pressure measurement model is established, the pressure measurement process is simulated by MATLAB software, and the simulation results are compared with the results of SpectraPlot. Finally, an experimental system was built for verification. The results show that in the pressure range of 1 to 2 atm, the simulation results of the absorbance curve are highly coincident with the results of SpectraPlot, and the maximum deviation of the integrated absorbance value is less than 8%. The relative error of the pressure measurement experiment results shows a trend of increasing with the increase of pressure. This conclusion provides a reference for the future research on the measurement of medium pressure gas by absorption spectroscopy.