Abstract: Direction finding is one of the central tasks of sonar. It is well known that most of the high-resolution algorithms have good performance provided that the positions of hydrophones are accurately known. The array shape usually departs from the planned original due to various reasons such as complicated terrain at seabed,ocean current,and even the method of deployment. If we still use the planed shape,performance of these high resolution algorithms will degrade severely. Therefore,before applying these al-gorithms to reality,we must have the array shape calibrated. Robust Capon beamforming (RCB) is a rec-ently proposed robust adaptive beamforming algorithm. It directly estimates the steering vector based on a steering vector uncertainty region,thus avoiding suppression of the signal of interest due to steering vector mismatch. In this paper,we propose a new array shape calibration method that borrows the idea from RCB,i.e.,we estimate the steering vector and further deduce the positions of hydrophones. Results of lake ex-periment show effectiveness of the proposed method.