The rotational speed of DC motors is an extremely important control quantity in the industrial production control process. With the improvement of industrial standards, the demand for speed control of DC motors in industrial production is also increasing day by day. Therefore, it is necessary to control the speed of DC motors. The paper conducts in-depth research, mainly introducing the characteristics and speed measurement methods of DC motors. The related concepts and principles of PWM pulse width modulation technology, the application of PWM in the speed control method of DC motors, the related concepts of PID and the control algorithm of PID are also researched in regards to control of DC motors based on single chip microcomputers and the incorporation of PID control into the system design. PID control is the most widely used and universal control method because of its simple structure, reliable operation, good stability, and easy adjustment. PID control algorithms have become the classic control method in industrial process control systems. The experiment proves that the PID algorithm can also be adopted for the DC motor speed control, so that the motor speed is stable and has quick response times. At the same time, the motor also has constant torque speed regulation characteristics.