The objective of this work is to introduce the design, simulation and control of a quadcopter, as an example of unmanned aerial vehicle (UAV).To fulfill this objective, a mathematical model of the quadcopter has been developed. The simulation of the model and controller design is developed in MATLAB/Simulink environment. Although it remains a complete nonlinear system, this paper operates with mathematical representation of the quadcopter and modeling of the intended system. A linearization of the obtained mathematical model has been achieved. In order to design the attitude controller, the transfer function of the brushless DC motors (BLDCM) which are responsible of the quadcopter motion is obtained using system identification techniques. A complete test experiment is described here to achieve this goal. The designed controller is assessed and simulation results are discussed.