Abstract: The multi-frame echo of high-speed maneuvering spacial target can be obtained by space-based radar. This paper propose a Multi-frame Coherent Integration Track-Before-Detect (MFCI-TBD) algorithm which is based on modified frequency compensation and Fractional Fourier Transform (FRFT) for target parameter estimation. The modified frequency compensation method can be used to correct range migration effect, then compensate the phase difference which is caused by the different frame, and the FRFT can be used to accumulated the energy of the multi-frame of the target echo, so the target’s parameter estimation result can be achieved. This method makes full use of the phase information which is between the multiple frame target echo, it can avoid the energy loss which is caused by conventional TBD method, the higher parameters estimation precision can be obtained in low SNR environment. Simulation results prove the effectiveness of the proposed algorithm.