The invention provides a C4F7N-CO2 gas insulated ring main unit with a rapid opening function. The gas insulated ring main unit comprises a circuit breaker and an isolation-grounding switch, each phase of arc extinguishing chamber of the circuit breaker is independently provided with a monostable permanent magnet operating mechanism, and a transmission rod of the monostable permanent magnet operating mechanism is vertically connected with each phase of arc extinguishing chamber of the circuit breaker. The circuit breaker, the isolation-grounding switch and the monostable permanent magnet operating mechanism are all sealed in a box body of the gas insulated ring main unit, and the box body of the gas insulated ring main unit is filled with an environment-friendly gas composed of a mixed gasof C4F7N and CO2. The gas insulated ring main unit has the advantages that the box body of the gas insulated ring main unit is filled with the environment-friendly gas composed of the mixed gas of C4F7N and CO2, the environment-friendly gas is high in electrical performance, the greenhouse effect brought by an existing SF6 gas insulated switchgear can be effectively avoided, and an ozone consumption effect is avoided.