The invention relates to the technical field of medical equipment, in particular to a pressure sore prevention pad for a semi-extended straight infrapatellar approach tibia intramedullary nail surgery, which comprises a pressure sore prevention pad body, the pressure sore prevention pad body is divided into four layers, the uppermost layer of the pressure sore prevention pad body is a backing layer, a hydrophilic fiber layer is arranged below the backing layer, a non-woven fabric layer is arranged below the hydrophilic fiber layer, and the non-woven fabric layer is arranged below the non-woven fabric layer, a liner bottom layer is arranged on the lower side of the non-woven fabric layer, a front side line of the non-woven fabric layer is aligned with a front side line of the liner bottom layer, sewing positions are symmetrically arranged on the front side line of the non-woven fabric layer along the center line, and a gap is reserved between a rear side line of the non-woven fabric layer and a rear side line of the liner bottom layer. Gaps are reserved between two side lines of the non-woven fabric layer and two side lines of the liner bottom layer, the backing layer is made of a polyurethane material, and the interior of the hydrophilic fiber layer is of a Kiss-Cut structure. According to the invention, blisters and infection in the peripheral area of the articular cavity surgical incision can be avoided, and the risk of iatrogenic skin bruise is reduced.