The invention provides a long-distance laser semi-active orientation measuring device based on polarization detection, relates to the technical field of long-distance target orientation detection, and aims to solve the problem that when an existing laser orientation measuring device performs long-distance target orientation detection, an input signal is submerged by system noise, affecting the detection capability of the laser orientation measuring device. According to the long-distance laser semi-active orientation measuring device based on polarization detection provided by the invention, a first 1/4 wave plate and a second 1/4 wave plate and a four-quadrant polarizing film are arranged in sequence in front of an optical lens group of a traditional laser semi-active orientation measuring device, the four-quadrant polarizing film is adjacent to the optical lens group, and the second 1/4 wave plate only covers the first quadrant of the four-quadrant polarizing film and the first quadrant of an APD detector. The long-distance laser semi-active orientation measuring device based on polarization detection is suitable for long-distance target orientation detection.