The invention discloses a solid gas generator filling device for a vacuum tank low-pressure test. The device comprises an electrical adapter, a flange base, a fixed cylinder and a connecting piece. The flange base is connected with a vacuum tank observation window through a connecting bolt; the fixed cylinder is connected with the flange base; and the electrical adapter and the connecting piece are connected to the two ends of the fixed cylinder. With the filling device, defects that the time and labor are wasted and the body of the test staff is exposed in a harmful combustion product environment for a long time because the test staff frequently enters and exits the vacuum tank in the traditional test method are overcome. The test time can be shortened and the labor cost can be saved. Thebody is directly and effectively isolated from harmful combustion products to realize man-machine isolation. The disclosed device is easy to operate; and the experiment can be completed only by usingtwo test staff members. The device is suitable for vacuum tank low-pressure tests of solid gas generators with various specifications and sizes within the outer diameter rang of phi 66.0 mm.