The influence of birefringence dispersion on the measurement sensitivity of polarization-mode coupling white light distributed polarization maintaining fiber sensor is analyzed and experimentally investigated. A numerical dispersion compensation algorithm is presented to calculate the coupling strength. The algorithm based on the interferogram envelope area is a constant though there exists the influence of birefringence dispersion on the fiber sensor and the algorithm ignores the optical intensity loss in propagation along the fiber. The interferogram envelope area can be obtained by the Hilbert envelope retrieval and nonlinear least square fitting, and then the polarization coupling strength can be obtained. The experimental result shows that the algorithm has a high accuracy, and the absolute deviation is less than 0.63 dB for short fibers.