Abstract: The time domain correlation algorithm has disadvantages of large computational load and low efficiency for 3D imaging. In view of this, this paper presents a dimensionreduced time domain correlation algorithm for 3D cylindrical array imaging, solving the aforementioned disadvantages. The proposed method adopts the Fourier transform in height and the time domain correlation in azimuth and range, which reduces the 3D time domain correlation to 2D time domain correlation, and thus effectively reduces the computational load. Additionally it preserves the advantage of time domain correlation method without interpolation and ensures the imaging precision. The computational load of time domain correlation algorithm, back projection algorithm and dimensionreduced time domain correlation algorithm are analyzed. The result proves that the proposed method has advantage in the application of cylindrical array imaging of human body. Finally, simulation results show that the proposed method has the validity and feasibility in application of 3D imaging of human body.