A distributed polarization maintaining fiber (PMF) pressure sensing system is presented based on polarization mode coupling in PMF. A 1050 m long fiber is tested and the measurement sensitivity and spatial resolution are determined. The relationship between coupling intensity and the size of the force as well as the influence of temperature on the system are tested. The experimental results show that the maximum detectable fiber length is longer than 1000 m. The measurement sensitivity and spatial resolution will decrease with the increase of fiber length. The temperature impact on this sensing system is very small when it is lower than 100 ℃. The influence of birefringence dispersion of the PMF on the system is also analyzed. The measurement sensitivity can be improved by a rotatable half wave plate to adjust the rotation polarization angle of the analyzer. The measurement sensitivity of the sensing system is 85 dB and the maximum spatial resolution is 98 mm by adjusting the rotation polarization angle of the analyzer.