Abstract: In this paper,the problem of the efficient coherent integrative detection of high velocity moning target with low SNR is investigated.Firstly,the characteristic of chirp radar's return is analyzed.And then it is pointed out that the main factor that influences the performance of the coherent integration is the envelope's migration between range cells.Finally,a new integrative detection algorithm,which is using divided frequency and replaced envelope,is proposed to resolve this problem.Monte Carlo test shows that,on the condition of-4 dB SNR,using this algorithm,the high velocity moving targets can be detected,with the false alarming probability under 10~(-6) and the detection probability above 98%.