Device and method for measuring phase retardation distribution and fast axis azimuth angle distribution of birefringence sample in real time. The device consists of a collimating light source, a circular polarizer, a diffractive beam-splitting component, a quarter-wave plate, an analyzer array, a charge coupled device (CCD) image sensor and a computer with an image acquisition card. The method can measure the phase retardation distribution and the fast axis azimuth angle distribution of the birefringence sample in real time and has large measurement range. The measurement result is immune to the light-intensity fluctuation of the light source.