The invention relates to a flexible wearable conductive fiber sensor and a preparation method and application thereof. The flexible wearable conductive fiber sensor comprises a support material and a conductive layer; the support material comprises an elastic core yarn and winding fibers wound in the external surface of the elastic core yarn in a spiral manner; and the conductive layer coats the surface of the winding fibers of the support material. The flexible wearable conductive fiber sensor uses a unique elastic spiral double-wrapping structure, and can sense stretching strain, a bending angle and torsional deformation.