Abstract: The target echo migration usually exceeds a range resolution cell, when the target is moving with a high velocity. Thiscauses Doppler frequencyspectrum aliasing, and makes it troublesome to accumulate the pulses.Theorily, when the high-velocity target’s signal is at low signal to noise ratio(SNR), accumulating for longer timecould develop the detection ability. However, during longer term accumulation, the waves of pulses may exceed several range resolution cells. This makes it much more difficult to pulses accumulation. Estimating speed before detection could develop detection abilityintheory.But in fact, it’s very difficult to measure the speed. Even realized, it needs much longer term to archive. This is very difficult to come true in practice.In this paper,theoretical derivationwill be carried onparticularly. Ittells why there would be rangemigrationand Doppler ambiguity, and how to compensate them. Based on the theoretical derivation,a modifiedmethodwhich is based on Keystone transform is put forward.The method is calculating the differences of all the points of pulses’peaks,which is get at different ambiguity factor.Note the Doppler ambiguity factor when the difference is smallest.This Doppler ambiguity factor can be used to compensate Doppler ambiguity as is shown below.Keystone transform can be realized by the method of SINC interpolation and the method of calculating Doppler ambiguity factor. This method is not restricted by the accumulation time, and doesn’t need to estimate the speed before detection.What’s more, this method couldcompensate the range migration and Doppler ambiguitywithout acknowledging the target’s speed.The resultshowsthat, compared with other methods,this method could compensate the range migration and Doppler ambiguity without acknowledging the targets’ speeds.It is not restricted by the detectiontime. It also develops the SNR of the pulses of high-velocitytargets, and Radars’ detection ability in wideband radar. This method is of great value in practice, especially in millimeterwaveradar