Abstract: In order to expand the applicable scope of electromagnetic model,a new approach was proposed after recombining unknown parameters about building and ground in this model.The new calculation process was consisted of two steps: initial building height firstly estimated by layover measurement of building roof,and then building height refined by electromagnetic model which was resolved in the system of simulated annealing.To validate this method,heights of three buildings were retrieved from a Radarsat-2 image with 3-meters resolution.The results show that the relative error of building height retrieval is less than 10% in the experiment data.