The utility model discloses a spiral spring with changeable length, including the spring body, spring body top is provided with interior pole, spring body bottom is provided with the loop bar, the loop bar internal diameter is than the big 0.2mm~0.5mm of interior shank diameter, the inside screw hole that all is provided with of interior pole and loop bar, the screw hole equidistance is equipped with three groups at least, interior pole surface is provided with the cylinder, the cylinder runs through interior pole, and the cylinder diameter all is greater than loop bar internal diameter 0.2mm~0.5mm. This product simple structure, convenient operation, application scope is wide, need not the coil spring according to the specific length of specific applications occasion customization, has practiced thrift the cost to the cycle has been shortened.