The invention relates to a knife for peeling a fruit core, which is a tool with simple use, convenient carrying and high safety. A knife body and a knife handle are made of stainless steel, and a knife sheath is made of plastics. The lowermost part of the knife is inserted into a fruit and is positioned at a position beside the fruit core, then the knife handle is held to rotate the knife along the probable fruit core, the knife is pulled out when the knife rotates at a certain degree, and afterwards two parts divided from the middle by the rotation of the knife are separated, so that the fruit core can be pulled out. The invention provides the feeling of safety and the feeling of novelty to people, is convenient to carry in outgoing at ordinary times and is safe. The invention has the advantage of low manufacturing cost and is especially worth being widely used in daily life.