In current research on unit maintenance schedule， the focused problems are reliability and economic. The equity problem always has been neglected. In market environment， such schedules will be dubitable for the generating companies. A new index———opportunity cost per capacity（OCPC） is proposed， which is used to evaluate the economic loss caused by unit maintenance. Besides reliability would be guaranteed by equivalent reserve capacity method， the economic index could be valued by mean value of OCPC， and the equity will be evaluated by the standard deviation of OCPC. Then integrated evaluation on economic and equity status can be calculated by the linear-weighted function. Based on these improvements， a new model for unit maintenance schedule is presented， and then the heuristic method is employed to solve this model. Finally， an example system is employed to illustrate the validity and feasibility of the method proposed.