The emergence of highly maneuverable weak targets has led to a serious degradation or even failure of traditional radar detection. In this paper, a coherent accumulation algorithm based on combination of scaling algorithm (SA) and discrete polynomial-phase Transform (DPT) is proposed in terms of the calculation burden and detection performance, which can, firstly, perform fewer times of speed parameter compensation based on SA for the transmitted signal, and selects the effective delay range of the target signal; secondly, for the extracted echo signal, the DPT algorithm is used to estimate the target speed and acceleration. The proposed algorithm analyzes the influence of time delay range, compensation speed and delay unit on the detection performance, and gives the improvement degree of output SNR and the amount of complex multiplication . Finally, the experimental data verify the effectiveness of the proposed algorithm in accumulation gain and parameter estimation. This method is for sub-optimal estimation, requiring much less computation than joint search methods, but performs better than cross-correlation methods.