The invention discloses a reliability testing device for a servo swing feeding system and a testing method. The problem is solved that a reliability testing device or a testing method does not exist currently. The device comprises the servo swing feeding system, a loading system and a control system; the servo swing feeding system comprises a workbench, a swing device and a servo oil path block assembly; the loading system comprises a servo motor and a speed reducer; the control system comprises an operation table and a laser interferometer; the workbench is arranged on a foundation, and the swing device and the servo oil path block assembly are arranged on the front surface and the upper end of the right end face of the workbench; the speed reducer is arranged on a lower cover plate of abase in the swing device, an output shaft of the speed reducer is in key connection with a swing main shaft in the swing device and the servo motor is arranged at the left end of the speed reducer andis in rigid connection with the speed reducer; the laser interferometer and the operation table are arranged on the portions, at the left and right sides of the workbench, of the foundation, and theoperation table is connected with the laser interferometer, the loading system and the servo swing feeding system through electrical wires. The invention further discloses the testing method.