At present, in the acoustic accuracy target measurements, it is generally required that the ballistic line and the target surface are perpendicular (Angle of intersection≤0.25 °), otherwise, the system will bring the error. In actual measurements, it is often difficult to ensure that the ballistic line is perpendicular to the target surface. Based on the theory of shock wave, a mathematical model of bullet shock wave cone surface is established in threedimensional space. According to the time difference of the shock wave surface passing through the sensor array, this paper presents a method of positioning the bullet point for the projectile oblique incidence.The model solves the coordinates of the bullet point in the threedimensional space, and the pitch angle α and the horizontal angle β of the ballistic line. The simulation experimental results show that the proposed model has high accuracy in oblique incidence.