Aiming at the problem of low resolution of millimeter wave human security inspection equipment using three-dimensional synthetic aperture imaging technology, a wavenumber domain IAA imaging algorithm is proposed by combining Iterative Adaptive Approach(IAA) technology and synthetic aperture imaging technology. IAA technique can estimate the energy of the signal source corresponding to each potential position, and bears the advantages of high resolution, low sidelobe and is suitable for single snapshot estimation. Through theoretical model analysis and simulation operation, the reconstructed rendering is compared with the traditional matching filter rendering to verify the effectiveness of the algorithm. At the same time, with the improvement of computing power, the performance of the algorithm will also be improved.