The present study establishes a thermal coupling model for TC4 titanium alloy plates containing prefabricated cracks using COMSOL Multiphysics. The objective is to analyze the relationship between ultrasonic wave propagation characteristics at various detection points and crack information to enhance crack characterization in inspection studies. The influence of detection point location, crack depth, and shape on the crack echo is investigated. The results indicate that with a fixed laser source position, a closer detection point to the crack leads to a shorter peak time and faster amplitude decay in the crack echo. Furthermore, the crack echo peak value increases as crack depth grows, displaying a rapid and linear growth pattern for depths exceeding 1.0 mm. The comparison of crack shape waveforms suggests that its impact on detection accuracy is negligible. By calculating the path and arrival time of the converted transverse wave and crack echo, the crack depth is characterized and located with an accuracy of less than 4%.