Abstract: The acoustical nonlinearity parameter B/A describes the nonlinear features of finite amplitude sound wave and may become a new important parameter for ultrasound tissue characterization. In this paper, based on the theory of nonlinear sound-by-sound interaction, the B/A tomography via parametric acoustic array is investigated, and the computer simulation for B/A tomography of lossless and attenuating media is studied by using filtered back projection algorithm, the influence of sound attenuation on B/A imaging is discussed and the attenuation correction methods are proposed.