The invention discloses a looseness test device for a bolt linkage structure, and an application method for the looseness test device. The device comprises an upper clamping tool, a lower clamping tool, and a testing sensing system. The upper clamping tool comprises an upper connecting board, a positioning centering assembly disposed on the upper connecting board, an upper clamping end and a right clamping end, wherein the upper and lower clamping ends are respectively disposed at the upper and right ends of the upper connecting board. The lower clamping tool comprises a lower connecting board, a lower clamping end and a left clamping end, wherein the lower clamping end and the left clamping end are respectively disposed at the lower and left end of the lower connecting board. The upper and lower connecting boards are provided with bolt grooves which are superposed. The device can achieve the looseness testing of the bolt linkage structure under the multi-mode effects (eccentricity, torque, axial alternating and cutting alternating loads), is simple in structure, is easy to operate, is low in manufacturing, is high in precision of control and testing, is accurate and reliable in testing data, can provide a test basis for the design and application of the bolt linkage structure conveniently and easily, and improves the reliability of the bolt linkage structure more effectively.