Abstract: DC motors have been widely used in the electromechanical systems due to its simple structure, ease of implementing variable speed control and low cost. In high accuracy servo control system, high control performance of DC motor is needed. DC motors have traditionally been modelled as IInd order linear system, which ignores the dead nonlinear zone of the motor. Unfortunately, the dead zone caused by the nonlinear friction would bring great effect to servo systems. This paper studies the non linear model of the DC motor and the effects of different types of friction in determining motor dynamics at low speeds using modelling and simulation with MATLAB simulink.