Abstract: In order to overcome the many principle defects of mass spectrometry and make up the deficiencies of TDLAS method, a laser absorption spectrum vacuum partial pressure measurement method based on dual-comb heterodyne spectroscopy was proposed. The advantages of the dual-optical comb spectrometer, such as broad band width, higher spectral resolution and fast measurement speed, are used to achieve non-invasive, high-speed, high-precision vacuum partial pressure measurement with aid of the multi-pass sample chamber that was utilized to increase the effective absorption length. The partial pressure of CH₄ was measured by 32 characteristic absorption peaks of CH₄ in the range of 3.322 2 to 3.413 0 μm. The maximum relative deviation in the measurement results was 5.45%, and the deviation of the average partial pressure was 0.85%. Through the uncertainty estimation analysis, the measurement results were consistent with the uncertainty analysis results. By fitting the N characteristic absorption peaks of the target gas and calculating the Average partial pressure, the measurement uncertainty of the vacuum partial pressure could be significantly reduced, and the reduction coefficient was about \frac1\left)\vphantom1N\right.\!\!\!\!\overline\,\,\,\vphantom 1N.