The invention relates to a three-dimensional motion measurement system based on digital image measurement. The system comprises a center control computer, a three-dimensional denoter, a first camera and a second camera. The three-dimensional denoter comprises a two-dimensional plane denoter and a single-sided mirror, wherein the two-dimensional plane denoter is used for being attached to the corresponding position of a target object, and the mirror surface of the single-sided mirror and the two-dimensional plane denoter are opposite and form an included angle of 45 degrees. The first camera measures motion of the two-dimensional plane denoter through the single-sided mirror, and the second camera measures the motion of imaging of the two-dimensional plane denoter in the single-sided mirror. The center control computer is in communication connection with the first camera and the second camera, and calculates three-dimensional motion of a target point according to the measurement results of the first camera and the second camera. The system simplifies installation and debugging process of the measurement site, and meanwhile, greatly improves measurement precision.