Abstract: The new evaluation approach for Economic Maintenance-free Period (EMP) for mechanical pumping wells is first presented aimed at some problems which existed in producing treatment of the mechanical pumping wells in Chengdao Oilfield. The EMP evaluating model of mechanical pumping wells is established and the calculated method of EMP is presented based on the theories of well production rate decline and well economic limited oil production. The calculated results show that the new approach is simple and effective, which present the reliable theory basis for improving the economy of the shore wells, and can be efficiently used to managing the offshore well production.