Recently aerial robots have become a popular platform for load transportation. In this paper we are interested in solving the problem trajectory tracking with the suspended load without previously knowing or defining the trajectory of the quadrotor. Exploiting the knowledge that this system is differentially flat we use it to control the trajectory of the suspended load. As a solution we propose a method based on reinforcement learning algorithm called least-square policy iteration (LSPI). The control input for the quadrotor is obtained from the LSPI algorithm in order to drive the quadrotor in the direction that ensures that the load tracks the given trajectory. This method is model free which makes it robust to model uncertainties and it can be implemented as an online learning algorithm. The proposed method is verified through simulation and experiments.