Abstract: The high renewable energy penetration in power system will increase the risk of frequency excursions. A reserve optimization formulation is proposed for emergency dispatch with the participation of interruptible loads in the event of significant power loss. Compared with the traditional reserve capacity optimization scheme,the proposed method considers the response time and ramp rate of conventional units and interruptible loads in the emergency dispatch process,and constructs an emergency reserve optimization model considering the lower limit constraint of segmented frequency so as to enhance the emergency disposal capability of the power system. Numerical results show that the proposed model can effectively achieve the economic dispatch and frequency stability objectives of the power system.