With the rapid development of manufacturing industry and to adapt to the current development of CNC engraving, the interpolation technology is optimized to changethe single-step feeding into multi-step feeding to improve the interpolation calculation speed and further improve the processing efficiency of products. This paper analyzes the problem of the lower machining precision of the linear interpolation algorithm, and proposes solutions to improve. On the premise of machining the straight line and after a large number of mathematical calculations and data analyses, the triangle interpolation algorithm is proposed. The core idea of the triangle algorithm is to change the single-step feeding into continuous multi-step feeding. Generally, the triangle interpolation algorithm can greatly improve the speed of interpolation.