Abstract: The acoustic nonlinear parameter B/A describes the nonlinear features of the propagation of the finite0 amplitude sound wave and may be a new parameter for the ultrasound tissue characterization. In this paper, as a new method, the nonlinear parameter B/A computed tomography in reflection mode is proposed by using a compound transducer. Based on the theory of propagation of reflected second harmonics and the insert-substitution method of the finite amplitude sound wave, the theoretical approach for computer reconstruction of B/A tomography in reflection mode is proposed. The computer simulation and experimental images of some fluids and tissues are also presented in this paper, and results coincide well with the sample models.