Abstract: Because the translation hypothesis of optical flow method can not accurately describe the form of motion after tissue compression, so we proposed a new ultrasonic elastic imaging algorithm. It was assumed that the deformation of the tissue was affine transformation when the probe was pressed to the tissue, and the displacement and strain distribution were estimated simultaneously by the optical flow method combined with the prior estimation. In order to verify the effectiveness of the algorithm, the imaging quality of the algorithm and the other imaging algorithm were compared with the simulated radio frequency echo signal. The results show that the new algorithm is higher in signal to noise ratio (SNRe), contrast to noise ratio (CNRe) and running speed than the contrast algorithm under 8% compression. The results show that the new proposed algorithm can effectively estimate axial displacement and axial strain in the case of large compression.