The invention provides a 1000kV/500kV/220kV electromagnetic looped network looping-off opportunity selection method. Specific analysis is conducted in such aspects as the stability characteristic of a power grid, short-circuit currents and the fact of whether a high-voltage-class failure will cause a low-voltage-class cascading failure or not, and evaluation is conducted on the safety and stability characteristics and operation of a system from multiple angles. All steps of the method are based on related power grid planning and engineering researchable design; in addition to conventional emulating calculation, a typical expert theory model and method are also combined, a reference basis is provided for electric power system planning and design and actual power grid operation, and important technical support is provided for safe and stable development of an ultra-high voltage grid.