A novel unit maintenance scheduling（UMS） model based on the competitive market mechanism is proposed. Firstly， according to the cost / benefit analysis， each producer determines maintenance bidding costs（MBCs） of its generating units， which are submitted to the independent system operator（ISO） and can be utilized to calculate the satisfaction degree（SD）. These two indices both can represent the producer's attitude of continuous operating or maintenance outage of its own generation units. Subsequently， a UMS function is developed to schedule the generator outages considering MBCs， SDs and the possible load curtailment in the system. Moreover， a SD-based expense settlement method is presented to ensure the no-profitable nature of the ISO. Simulation results on IEEE-RTS system indicate that the proposed scheme can guarantee the system adequacy and the producers' benefits while ensuring the market fairness.