Quadrotors are types of Unmanned Aerial Vehicles (UAVs) which have unique features compared to conventional aircrafts because of its vertical take-off and landing capability, flying in small areas and its high maneuverability. Also the relatively simple, economical and easy flight system of quadrotors, makes it to widely used as a good platform for development, implementation and testing a variety of control methods. One of the robust control methods is sliding mode control. In spite of the high capabilities of this approach, it has a main problem which is high frequency switching of the control signal witch is known the chattering phenomenon. In the past several decades, fractional order differential equations have been implemented in engineering application field, including controllers design and provided the possibility of using controllers for improving the performance of system. In this paper, a fractional order sliding surface has been employed for designing sliding mode control rule for quadrotors. The main objective of this study is to improve the performance and reduce the chattering phenomenon in sliding mode method. In this regard, by introducing sliding 〖PD〗^α surface, the control rule is designed in two different modes of 0