The invention provides a detection device of the torsional deformation of a hoisting hook. The device comprises a clamp, a reference hook frame and a slide measurement frame, wherein the reference hook frame is designed into a shape of a theoretical central line of a hook to be measured; and the slide measurement frame measures an actual central line in a slide mode along the reference hook frame. The invention also provides a detection method of the torsional deformation of the hoisting hook, which comprises the following steps: clamping and fixing the reference hook frame on a handle part of the hook to be measured through the clamp and a positioning pointer welded on the reference hook frame; operating the slide measurement frame and recording a lateral outline central line of the hook to be measured; fitting out the actual central line; and comparing the theoretical central line with the actual central line to calculate out a torsional deformation angle. The invention has quick and convenient measurement process, no need of extra shut down, quantitative and objective measurement result and simple manufacture and is suitable for inspection and detection of various hoisting hooks.