This paper proposes a contact algorithm for gear pairs based on discrete tooth surface information, applied to both transmission systems with intersecting axes and parallel axes. It is designed to address the fundamental issues of gear contact for diverse and complex tooth surfaces under various external conditions. By discretizing the surfaces into a unified set of points, the algorithm achieves compatibility across varying surface representations. The initial gap function is introduced to compute the distance between meshing surfaces and to identify matching contact points, considering potential gear displacement caused by external disturbances. A C-language program was developed based on the proposed contact model, enabling efficient calculation of contact points on complex tooth surfaces under inter-tooth interference conditions. The effectiveness of the algorithm was validated through a calculation example, demonstrating its accuracy, precision, and superior computational efficiency. The methodology can be applied to verify the contact pattern of gear pairs both during tooth surface design and after modification. By incorporating surface data obtained through various methods, such as scanning or design-based equations, the model’s applicability is further enhanced, making it a versatile tool for modern gear design and analysis.