Abstract: In order to improve the real-time speed control capacity of variable speed pigs when they run at high speed or their speed rises suddenly, and to overcome serious speed distortion of odometer wheel speed measuring systems caused by the slippage of odometer wheels, a new electromagnetic (EM) speed measuring system is developed on the basis of EM induction principle, combined with the working principle of variable speed pigs. The new system is mainly composed of magnetization unit, speed detection unit, demagnetization unit, support wheel carrier and mounting cylinder. After analysis performed on electromagnetic theories, simulating design is conducted specially for magnetization units and speed detection units, and the design and installation essentials of the system are illustrated in detail. In the light of its design program, a speed measuring and calculating method based on speed ratio is proposed. Then, its feasibility is demonstrated by means of simulations. This system can meet the requirements for real-time speed measurement when variable speed pigs run at high speed or their speed rises suddenly.