In this paper, we propose a new method for simulating three-dimensional (3D) ultrasonic wave propagation using P-Spice like simulator. We use a one-dimensional transmission line model to implement the diffraction losses. In order to simulate the beam pattern considering axial and radial orientations, we calculate the diffraction losses in 3D space. First, we express the radiated field using a set of Gaussian beams. Calculating the average pressure over the receiver surface allows us to determine the diffraction losses. These losses are then incorporated into the P-Spice model via the G parameter which is axial and radial orientations dependent. Comparison between P-Spice simulation and analytical model results shows good agreements.