This study addresses how animals select the right strategies for motor sequence learning without any prior knowledge of correct sequence or task constraints. We developed a motor sequence learning task in which rats learn to press levers on the walls of an octagonal operant chamber in an unknown from intracranial self-stimulation reward only after the completion of the entire sequence. One rat could learn three-step sequence among four levers with more than 80% accuracy after 2000 episodes during 20 hours of training. We observed non-monotonic changes in their lever press sequence features. Correlation analysis between the motor sequences of rats and those from reinforcement learning simulations by the Q-learning algorithm with different length of memory indicated that the state variables and learning parameters changed with the progress of learning. These results suggest that rats can flexibly choose appropriate learning methods and parameters in accordance with learning progress.