A spatial variable resolution scanning three-dimensional (3D) imaging method is proposed to address the problems of high redundancy of point cloud and low accuracy of image reconstruction in traditional fixed-resolution scanning 3D imaging. A model of multi-echo and spatial variable resolution scanning imaging is deduced. Target information is extracted by decomposing multi-echo to achieve high resolution depth image reconstruction. The model is verified by comparative experiments. The results show that compared with the traditional fixed-resolution scanning imaging method, the sampling rate of the proposed method is only 50% under the comparable imaging quality, which effectively reduces the redundancy of the point cloud. The results can support the related application of 3D imaging.