In traditional through transmission ultrasonic detection for curved components with variable thickness, the amplitude of receiving pressure was unsteady and the signal to noise ratio was always low. In order to solve this problem, an acoustic modeling method, called multi-Gaussian beam superposition technique was introduced into the curved component ultrasonic detection system. A receiving pressure model was established to analyze the effect on receiving pressure under different parameters. Analysis and the experiment results showed that the receiving pressure is very sensitive to the probe position and orientation. The angle existed between ultrasonic beam propagating path and probe position and orientation planning by conventional path generation method shouldn’t be ignored. Taking bi-cubic B-spline surface workpiece for example, a new probe position and orientation planning method was proposed based on tracking ultrasonic beam propagation. The triggering probe position and orientation was planned firstly by regular method, then the receiving probe position and orientation was decided by tracking beam propagation form the trigger probe. Compared with the conventional method, practical application showed that the receiving signal is better and the detection results are more accurate by the proposed method.