To meet the demand of visualization in port machinery flaw detection, the electromagnetic tomography (EMT) technology is projected to detect and reconstruct metal structure flaw. Landweber iterative algorithm is a kind of traditional image reconstruction algorithm in research of EMT, but it does not work well when it is used directly in image reconstruction of metal flaw. Firstly, the region of interest is defined according to the characteristics of the sensor. On the supposition that the flaw has been detected and moved into the region of interest, the Landweber image reconstruction is carried out which gives better result, but the shortcoming is that the flaw detection and image reconstruction cannot be fulfilled at the same time, which means that the whole process is timeconsuming. Then, based on the characteristics of the sparse distribution of the metal structure flaw, the subspace pursuit (SP) algorithm which is a kind of sparse reconstruction method is used for flaw detection and image reconstruction. The simulation results show that the SP algorithm performs is better than the classical Landweber algorithm in the aspects of image reconstruction quality, algorithm robustness and so on, the flaw detection and the reconstruction are accomplished simultaneously.