Abstract: In this paper, a two-dimensional physical model made of "wood board" and "plexiglass board" is adopted, and three square holes of different sizes and positions, filled with gypsum are added to the model. The same observation system is arranged for the two physical models to form the same ray mode. Under the condition of equally spaced rectangular pixels, the integration step size of each ray (the length of the ray segment passing through a single pixel) is a constant. The travel time data of each transmitted wave ray (i.e. the "observed value" of the Radon transform line integral) is collected by the ultrasonic instrument along the designated ray. The "algebraic reconstruction method" (ART addition modified iteration method) is used to solve the discretized equations of the Radon transform, and the CT digital image of the two-dimensional physical model is reconstructed. In the reconstructed model CT digital image, the existence and location of "gypsum hole" can be effectively identified, which verifies the effectiveness of "algebraic reconstruction" CT imaging technology and its recognition of model structure. This paper is basic research of addition modified iteration ART and provides practical application reference for those who interest in" Algebraic Reconstruction Technique".