Aiming at the problem of high-precision time delay estimation under the condition of limited memory, this paper uses the cross power spectrum of the received signal to reconstruct two time-varying sequences related to the array signal and a time invariant constant sequence independent of time. Through multiple FFT and IFFT combination operations, as well as point multiplication, reconstruction and replacement of the sequence, high-precision and high-gain fast time delay calculation is realized, which are UUV, potential target The large acoustic array of unmanned platforms such as buoys and manned platforms provides technical support for high-precision time delay estimation, azimuth estimation or passive positioning.