The invention discloses a single cutting-edge cutting knife exclusively used for a tendon sheath, and relates to the technical field of hand surgical scalpels. The single cutting-edge cutting knife exclusively used for the tendon sheath includes a blade, a cutting edge and a connecting end, the blade is arranged on the upper end of the cutting edge, the tail end of the blade is connected with theconnecting end, the working end of the cutting edge is oriented towards the head end of the blade, the cross section of the blade is of an arc groove structure, and the connecting end is provided witha mounting groove; when in using, the connecting end is firstly connected with a surgical knife handle, after the surgical knife handle is connected, a transverse incision is cut on skin on the tendon sheath of a finger, the skin at the incision is turned up by using surgical tweezers, the head end of the blade is inserted in the lower part of the tendon sheath, and pushed up in the direction ofthe finger, the blade cut the incision on the tendon sheath of a patient, and minimally invasive is made.