This thesis investigates the control problem of quadrotors with commercial parts. Because of the convenience and easy operation of quadrotors, wider and wider applications of quadrotors are initiated. By purchasing a commercial quadrotor or or assembling a quadrotor with commercial parts one can avoid annoying process of designing or fabricating quadrotors. However, a commercial quoadrotor installed with our own payload will cause the change of dynamical characteristics, leading to the consequential change of control parameters. In this thesis, a quadrotor is assembled from commercial parts and will serve as a research platform in the future. In order to reveal its dynamics, we adopt a simple way of system identification to identify the dynamical parameters of the quadrotor. Then proper control parameters are designed based on the identified system. Numerical simulations and flight tests are employed to verify the correctness of identified parameters, and the validity of the controllers.