The invention discloses an assembly line operation prepackaging automatic filling device for an attitude and orbit control power system. The assembly line operation prepackaging automatic filling device comprises a vacuumizing unit, a propellant supplying unit, a cleaning and blowing unit and a product unit. The vacuumizing unit is composed of a vacuum pump, a vacuum gauge tube, a vacuum meter, avacuum solenoid valve, an air cavity vacuumizing opening, a liquid cavity vacuumizing opening I, a liquid cavity vacuumizing opening II, a pneumatic vacuum control valve I, a pneumatic vacuum controlvalve II and a vacuumizing pipeline. The propellant supplying unit comprises a propellant supplying opening I, a propellant supplying opening II, a pneumatic propellant control valve I, a pneumatic propellant control valve II, a propellant control solenoid valve I, a propellant control solenoid valve II, a propellant control solenoid valve III, a propellant control solenoid valve IV, a propellantstorage container, a manual propellant control valve I, a manual propellant control valve II, an electronic balance, a manual pressurizing control valve, a gas pressurizing port, a pressure gauge anda filter. The assembly line operation prepackaging automatic filling device aims to realize fast, stable, automatic and assembly line prepackaging filling operation of products.