The invention aims at providing a real-time monitoring and charged gas supply device for an SF6 gas in a circuit breaker used for solving the technical problems of real-time monitoring and gas supplyof the gas in the circuit breaker. The device comprises an electric cabinet, the circuit breaker, a monitoring mechanism, a gas supply mechanism and a control system, wherein the circuit breaker is provided with a density detector tube, a gas regulator tube and an arc-suppressing pressure sensor; the gas supply mechanism comprises a gas supply tube, a gas supply tank, a gas supply electric controlvalve and a gas supply pressure sensor; the gas supply tank communicates with the gas regulator tube through the gas supply tube; the gas supply electric control valve is arranged on the gas supply tube; and the control system is electrically connected with the arc-suppressing pressure sensor, a gas density meter, the gas supply electric control valve and the gas supply pressure sensor separately. The real-time monitoring and charged gas supply device has the beneficial effects that the density of the SF6 gas in the circuit breaker can be monitored in real time, and intelligent inflation anddeflation can be implemented.