The utility model provides an experimental appurtenance of LTT change of current valve thyristor, includes insulated handle, insulator spindle, is equipped with two metal feeler levers on the insulator spindle top, is connected with the horizontal pole at insulator spindle top in the middle of two metal feeler levers, and the horizontal pole is the insulator, contact with the positive pole and set up respectively on the radiator of thyristor both sides in thyristor negative pole contact, the position that is equipped with two metal feeler levers with the insulator spindle top is corresponding, two metal clips that testing arrangement drew are connected respectively with two metal feeler levers that the insulator spindle top was equipped with. This device design the extension of insulated handle as the staff, also reduced the experimental degree of difficulty when having improved the security, the radiator that this instrument utilized the thyristor both sides is as the contact point, with the contact point of metal clip clamp in the thyristor both sides in the replacement traditional approach. Human resource and material resources can be saved in a large quantity. Efficient and safe risk is little.