Radio knives are common tools in surgery. The adhesion of the tip of a radio knife to the human body through the coagulation of blood is a severe problem. A solution to this problem, suggested by other authors, is to cool the tip of the radio knife. However, introducing a cooling system, such as circulating water inside the tip with a pump, requires additional wires and pipes and may also distract the surgeons. To overcome these issues, we consider the possibility of embedding a separate type thermosyphon to cool the radio knife tip without any additional wires and pipes. The important parameters are the tip length, tip diameter, inner tip diameter, enclosure ratio of the working fluid, and grip length. First, to clarify the heat-transport possibilities, the top of the tip of a separate type thermosyphon radio knife was heated by a ceramic heater; this was done to measure the temperature difference between the radio knife tip surface and a heat release part. Second, suitable values for the tip length, diameter and other important parameters were considered. It was concluded that the highest cooling efficiency is obtained when the heating area is limited between 200 and 250 mm2 of the knife tip surface area. The inner pipe was indispensable to transport generated heat from the tip to the radio knife end. Consequently, it was revealed that the effective diameter of inner pipe was 0.48 mm in this research. To simulate the conventional surgery situations, the radio knife tip was immersed to blood and applied voltage to generate heat at the tip. It demonstrated 45.9 degree C at the maximum temperature while it was activated. Furthermore, the coagulation at the peripheral of the tip was observed, accordingly, the separate type thermosyphon radio knife exhibited a stop bleeding ability.