This paper studies the peripheral mechanism contributing to the tremor of human body. It is known that the reflex loops in peripheral nervous system have significant influences on the tremor. A neuromusculoskeletal model with several reflex loops is developed to explore the origin of tremor. The muscle model is developed based on a Hill-type muscle model. The feedback loops include the spindle organ, Golgi tendon organ and Renshaw cell. Their effects are investigated quantitatively in detail. Some results are in accordance with the previous research. Meanwhile, some new findings are proposed according to the simulation study.