The present invention provides a multi-bolt loosening test machine for flange with tension, bending and torsion compound loading. The multi-bolt loosening test machine for flange with tension, bending and torsion compound loading uses a transverse load generated by a three-phase asynchronous motor as a bending load applied to a flange, uses a tension force generated by a hydraulic puller as an axial tension load, and uses a torque generated by a servo motor as a torque load applied to the flange. The test machine is different from the current device that can apply two compound loads to a single bolt, and can apply three compound loads to the multi-bolt connection flanges. The present invention can isolate three compound loads from each other without interference, and display the applied loads in real time.