In engineering practice, it is of great significance to design a controller which is easy to use and maintain for the uncertainty of industrial process. Newton's law was one of the most familiar physical laws for engineers and technicians. Based on Newton's law, this paper proposes a model-free uncertainty control system and its design method. By constructing three state variables of the controlled system, i.e., position, velocity and acceleration, and applying Kalman filter theory, an observer based on Newton motion law (ONLM) is designed. And then a closed-loop compensator is designed according to the position, velocity and acceleration, and then a model free control system (MFCNLM) is brought into being, which makes the system output track the desired output trajectory. Furtherly, this paper puts forward a PID controller design method based on the principle of Newton motion law, and analyzes and demonstrates the Newton motion law of MFCNLM control method and PID control method in control system design. The design method proposed in this paper does not need the mathematical model of the controlled object, but only needs the control engineer to give the expected transition time $T$ of the closed-loop control system. The results show that the proposed method has good control quality and robust performance for uncertain systems.