Aiming at the problem of three-dimensional measurement of the inner surface of deep-hole parts, this paper proposes a new three-dimensional reconstruction algorithm for the inner surface of deep-hole parts. This method uses a telecentric lens and a multi-line structured light generator to obtain structured light images of the inner surface of deep-hole parts, combined with the morphological characteristics of deep-hole parts, establishes a three-dimensional projection model of a telecentric lens based on a cylindrical coordinate system, calculate the radius of the measurement point with the offset in image, and the 3D reconstruction point cloud of the measurement image is obtained on this model. The experimental results show that the root-mean-square error of this method is within 0.03mm in the measurement of a deep hole with a diameter of 155mm, and the measurement accuracy meets the requirements of the system, which provides a data basis for accurately analyzing the state of the inner surface of deep-hole parts.