In the 5GNR system, the influence of noise cannot be ignored in the channel estimation process at the receiving end, and the traditional LMMSE channel estimation algorithm will have a huge computational load. Therefore, a sliding correlation matrix method based on DMRS is proposed to reduce the complexity of the algorithm. Firstly, the optimal sliding correlation matrix and the number of subcarriers output for each sliding are obtained through simulation, and then output the channel estimation values of frequency domain subcarriers through the sliding window to complete the entire channel estimation; In the time domain, the system performance is further improved by the hybrid interpolation method. Simulation results show that compared with the LMMSE algorithm, the bit error rate of the algorithm is improved by less than 1dB, and the complexity is reduced by 99.74%, which meets the needs of engineering.