The imaging of through-the-wall radar is greatly influenced by wall parameters. Facing the unknown wall

traditional imaging algorithm is a rough estimation of its parameters

which leads to the decrease of the target after the wall imaging quality and the inaccurate positioning. Based on back projection（ BP） algorithm

an effective and multi-level prediction algorithm for wall parameters is proposed by analyzing the backwall echo. The algorithm shrinks rapidly range of estimated parameters by firstly using"target location curve intersection method"

and then through the image entropy measurement indicator further determines the specific parameter values. The whole process makes reasonable arrangement for the configuration of the transceiver antenna

and improve the efficiency and precision of parameter estimation. The simulation results show that this algorithm can realize the accurate prediction of wall parameters on the basis of single target behind the wall imaging.