Abstract: The nonparaxial multi-Gaussian model can overcome the limitation of paraxial approximation and guarantee the efficiency of sound field simulation under the larger deflection angle. Based on the Rayleigh integral model in double media and the nonparaxial multi-Gaussian beam model in single medium, a nonparaxial multi-Gaussian beam model of a single rectangular array for shear wave detection is proposed. According to the delay time of each array for beam steering and focusing, a radiation beam field of ultrasonic linear phased array for shear wave detection based on a nonparaxial nmlti-Gaussian beam model is obtained through accumulation accordingly. Then this paper calculates the radiated sound field produced in the interrogated steel medium by a linear phased array transducer mounted on an acrylic wedge, and the comparative analysis between the proposed model and the paraxial nmlti-Gaussian beam model is performed to simulate the beam field with double interfaces. Simulation results show that the proposed model runs faster than the paraxial multi-Gaussian model, and it takes about 1/13 time of the latter. In addition, comparison analysis results indicate that the proposed model can cover the bigger inspection area, has more concentrated energy, and is more suitable for the far field detection.