This paper mainly studying how to build a Dynamometer(Dyno), and some implementation of Dyno. We design a new mechanism for torque measurement, hoping to avoid noise and to cost down. The Dyno we Designed also measure power factor and efficiency of motor system and this make the dyno a good tool when studying motor system. Implement of this dyno including new-type torque measurement, feedback control, sine wave identification, circuit design, and software design. Sine wave identification is used to identify power factor and efficiency. This paper dedicate in background studying and some basic implementation. I hope this paper can help others when they’re studying Dyno.