Abstract: In order to measure the motion state of the unstable and fast-swirl non-cooperative target, a measurement method based on sequence images of monocular camera was proposed. First, the measurement principle was derived and proved according to the projection geometry of the target and the detector. Then, considering the characteristics of the space lighting environment, an image processing method based on maximally stable extremal regions(MSER) features was proposed to extract the projection angle. Moreover, according to the multi-frame sequence projection angle value, the spin rate of the non-cooperative target was calculated by setting a reasonable polynomial fitting model. Finally, the effectiveness and measurement accuracy of the proposed method were further verified by on-orbit data. Experimental results show that, for the 60°/s fast-spinning non-cooperative target, a monocular camera with 1Hz frame rate is used to observe the target in 150 seconds, the mean measured value by this method is 60.07° and the standard deviation is 0.05°/s. Therefore, a stable, reliable and highly precision spatial non-cooperative target motion state measurement is achieved.