Based on Cortex-M3 kernel,STM32 has distinguished feature such as low-power,abundant internal peripherals,quick processing speed and so on.It's typically applied in data acquisition system.Step motor rotational speed control design based on STM32 is introduced in this paper.Comparing with traditional singlechip,it has many advantages such as fast processing and perfect funcion.STM32 manipulate step motor according to sensor signal and display operating state.This article has given details in hardware design and software procedure,attaching part of experiment description.This experiment system has proved to be stable and reliable through practice,which is supposed to be great effect of experiment teaching.