The ordinary DDA interpolation algorithm has the following shortcomings: the feed speed is not fast enough, the interpolation error is too large, the pulse distribution is uneven. Employing improved DDA as the interpolation algorithm, taking advantage of STM32 microcontroller, which was based on ARM CorterM3 processor as the interpolation control core, DDA hardware interpolation system was designed, and the highspeed, highprecision interpolation was achieved. Making use of Keil uVision 4, ordinary DDA and improved DDA algorithm programs were designed based on C language, then the interpolation results of the two methods were contrasted. The interpolation result shows that: comparing with ordinary DDA, the improved DDA has increased to some extent on the interpolation speed and precision, and the distribution of the controller pulse overflow is more uniform.