For the low efficiency of phase stereo matching in binocular structured light 3D reconstruction, a fast matching method with polar line approximation is proposed. Firstly, the polar lines are described based on the intersection line between the optical centers of the two cameras and the left pixel forming plane and the right imaging plane; the corresponding polar lines of some regions in each row of pixels are approximated, and the continuity constraint of stereo vision is combined, so that the isolated search for matching phase along the respective polar lines is replaced by the continuous search for matching phase along the approximate polar lines in the region; meanwhile, the global uniform partitioning is realized by combining the bit pose characteristics of binocular cameras to avoid repeated partitioning for each row of pixels; the calculation is assisted by the table look-up method. The global uniform partitioning is combined with the binocular camera pose characteristics to avoid repeated partitioning for each row of data. The experiments show that the average error of the point cloud obtained after stereo matching is 0.436 mm, which is within the acceptable error range, and the average speed of stereo matching calculation is increased by 10.18 times.