The invention provides a radar echo delay coherent simulation method based on a digital radio frequency memory, which includes the following steps: S1, a simulator extracts the envelope of radar transmitted signal pulses, and uses a local clock to perform clock counting N3 in N2 radar transmitted pulse cycles; S2, the echo delay analog quantity tau'(n) after correction is calculated; S3, the nominal clock cycle number k' of the corresponding simulator is calculated according to the echo delay analog quantity tau'(n); and S4, the readout sequence of digital medium-frequency signals obtained after processing by the simulator and saved in a digital radio-frequency form is controlled using the k' value, thus completing radar echo delay simulation. Through the method, coherent simulation of radar echo delay can be completed quickly.