Disclosed is an optical needle comprising a coupling seat, a needle body in connection with the coupling seat and at least an optical fiber. The needle body comprises a lightguide groove extended along the length direction of the needle body to accommodate a portion of the optical fiber. The coupling seat provides a junction plane to couple a light source. An end of the lightguide groove is aligned with the junction plane, so to align an end of the optical fiber with the junction plane. The optical needle is characterized in that the long axis of the optical fiber reduces from a section aligned with the junction plane to an end adjacent to the needle body. A method for preparation of the optical needle is also disclosed.
