The invention discloses a sulfur hexafluoride recovery and low-temperature liquid injection filling system and an operating method thereof and relates to the fields of gas recovery and low-temperaturefilling. The traditional direct low-temperature liquid injection filling system has a behavior of discharging SF6 gas into atmosphere, and great damage is caused to the environment and operators. Thesulfur hexafluoride recovery and low-temperature liquid injection filling system disclosed by the invention comprises a recovery device and a filling device, wherein the recovery device is used for recovering sulfur hexafluoride; the filling device is connected with the recovery device and is used for filling; the filling device comprises a filling distribution tank, a vacuum pump, a plurality ofvalves and a connecting pipeline; the connecting pipeline comprises a tail gas pipeline, a filling pipeline and a vacuum pipeline; at least one filling pipeline is arranged on the filling distribution tank; valves comprise a filling pipeline tail gas valve, a filling valve and a filling pipeline vacuum valve; the filling pipeline tail gas valve is arranged on the tail gas pipeline; the filling valve is arranged on the filling pipeline; and the filling pipeline vacuum valve is arranged on the vacuum pipeline. According to the technical scheme, the filling safety can be effectively realized, the tail gas recovery is effectively realized, the environmental protection ability is improved, and the safety of operators is improved.