An Aerial Robot or Unmanned Aerial Vehicle (UAV) is an aerial vehicle that provides its flight condition using aerodynamic forces. This vehicle can be named as an autonomous robot. This robot is an under-actuated system and is inherently unstable. Thus, the control of this nonlinear system is a problem for both practical and theoretical interest. So, the goal of this research is to compare it with highly nonlinear dynamic system of Octorotor which is difficult to control in many cases and causes instability in this Unmanned Aerial Vehicle (UAV). At first, the structure of Octorotor is studied in this paper in order to increase power, better ability to carry a load and to increase resistance into the distribution. Also, the electronics and mechanics of this robot are studied in some sections. Then, in the following, in order to control attitude of robot with introduction of dynamic system, one of the most common implemented controllers is applied on this robot. Initially, this process is done on the dynamic model of robot by Matlab/Simulink software and finally, implementation of this controller is applied on a fabricated Octorotor during a real flight in autonomous trajectory tracking in outdoor environment. Finally, the study of sensors results is also shown.