Abstract: Although the existing research on mine power grid relay protection setting has studied the setting methods of mine power grid relay protection under different operation modes, but it has not studied the setting method that applied in the automation system of mine power supply and dispatching. Therefore, the setting value could not be calculated in real time as the operation mode of the mine power grid changes. The new setting value can not be given to the protection that does not meet the requirements. To address the above problems, on-line relay protection setting system for mine power grid considering multi-scenario operation mode is proposed by defining the combination of a certain type of circuit breaker status on the bus power side of the outgoing line of the protection position as a mine power supply system scenario. The system uses the scenario corresponding switch state matrix to calculate the scenario area matrix and scenario network branch impedance matrix of the mine power supply system. Then the system calculates the maximum and minimum system impedance of the scenario based on the scenario area matrix and scenario network branch impedance matrix. As the change of breaker switching state or the scenario is monitored, the real-time switching state of the breaker is automatically read. The scenario class with the state change switch is found through the scenario switch information matrix. A scenario class is selected according to the number of switches in the scenario class, and the setting value of protection corresponding to the scenario class is calculated. Based on the calculation result of the setting value, it is reviewed whether the protection performance meets the requirements.If not meeting the requirements, on-line setting calculation will be carried out. If meeting the requirements, then the calculation of the scenario class will be completed, and the next scenario class will be calculated until the all scenario classes being calculated.The application results show that by communicating with the mine power supply dispatching automation system, the protection range of the on-line relay protection setting system for mine power grid considering multi-scenario operation mode can adapt to the requirements of relay protection devices in various operation modes. Moreover, the method avoids the rejection and misoperation of relay protection devices caused by the setting value not meeting the requirements after the change of operation mode.