Abstract: Point-by-point comparison method is a commonly used algorithm in laser marking system. Interpolation plays an important role in controlling laser trajectory and fitting image trajectory. Because of its intuitive operation, uniform pulse output and convenient adjustment, point-by-point comparison method is a more suitable interpolation algorithm for marking machine system. But the traditional point-by-point interpolation algorithm has some problems, such as low accuracy and slow speed. In order to improve the performance of this algorithm, the traditional point-by-point comparison interpolation algorithm is improved, and the calculation and simulation are carried out. The results show that the precision and speed of the improved comparative interpolation algorithm are improved significantly.