The invention discloses a torsion testing device for testing the bonding strength of lamellar composite strips, and belongs to the technical field of testing devices for the bonding strength of the strips. The torsion testing device comprises a control system, a torsion mechanism connected with the control system, a strip fixing and tension mechanism and a base, wherein two parallel sliding railsare arranged on the base; the torsion mechanism and the strip fixing and tension mechanism are arranged on the sliding rails by a sliding block; and two ends of the sliding rails are fixed on the base by sliding rail fixing blocks. The device can be used for testing the bonding strength among layers of the composite strips with two or more than two composite layers, and the effective torsion length is kept within the range of between 20 and 250 millimeters. The device is simple and quick in operation and uniform in positive and negative torsion, can test the fatigue life of the strips by repeated torsion, has wide size range of samples and particularly has 250-millimeter length, improves the effectiveness of testing samples, has stable torsion and high repeatability, and solves the problem of inconsistent judgment caused by personal factors.