The present invention relates to a cladding structure of an optical fiber laser capable of allowing efficient optical pumping at a core of the optical fiber laser using the concept of quantum chaos, and more particularly, to a cladding structure of an optical fiber laser, which enables efficient pumping in an optical fiber by constructing the cladding in a non-integrable structure for causing quantum chaos so that a pumping beam injected in the cladding can pass through a core of the optical fiber as much as possible. To this end, the present invention provides a cladding structure of an optical fiber laser having a core formed of a laser medium and a cladding surrounding the core, wherein the cladding has a sectional structure for causing non-integrable quantum chaos so that a pumping beam injected in the cladding is reflected on the boundary of the cladding and then pumps the core of the optical fiber laser, and the structure for causing the non-integrable quantum chaos is a structure having an unstable path on which upon injection of a beam, a slight change of initial direction of the beam results in a completely different subsequent advancing direction of the beam.