Abstract: Ground based Space Surveillance Phased Array (SSPA) Radar usually works on the mode of multi-tasking and multi-objects, and radiates objects in time segmentations. Aiming at this point, taking the ballistic missile (BM) as an example, the multi-section time segmented radar returns model was developed in the paper. And then the micro-Doppler modulation characteristic induced by finned missiles’ spinning motion was analyzed. The feasibility of using microDoppler modulation period as an important feature parameter to recognize the BM target was opened out in theory. According to the characteristics of the multisection signals, the Radon-p-STFT method was proposed to estimate the half radial acceleration. Based on the acceleration compensated signal, the micro-Doppler modulation period was extracted successfully utilizing circular Average Magnitude Difference Function (AMDF).