The invention relates to an active controllable fiber grating, which is formed by power supply, a plurality of resistance wires, two insulating boards, optical fibers and a lead wire, and is characterized in that a plurality of resistance wires are respectively arrayed vertically on wire chases of the two insulating boards according to the cycles of the needed gratings; the optical fibers are clamped in the wire chases of the two insulating boards and contacted with a plurality of resistance wires; the refractive index of the optical fiber is sensitive to temperature; a plurality of resistance wires are connected with an anode and a cathode of the power supply in parallel through the lead wire. The active controllable fiber grating of the invention has the advantages of simple structure, convenient operation and easy realization, and can realize the formation and disappearance of the fiber grating through connecting or interrupting current.