The invention discloses an optical limiter with a small limiting threshold value. The optical limiter with the small limiting threshold value comprises a beam expanding collimation system, a radially polarized beam generation system and an optical limiting system. A linearly polarized laser beam is converted into a radially polarized beam through a liquid crystal polarization converter. The laser beam is focused through a convex lens. Nonlinear absorption materials are placed on the focal plane of the lens. The light intensity of light passing through a sample is nonlinearly reduced along with increase of the incident intensity through the two-photon absorption effect of the materials, in this way, the optical limiting purposes that when the light intensity is low, the transmittance is high, and when the light intensity is high, the transmittance is low are achieved, and human eyes and optical elements are effectively prevented from being damaged by a high power laser. By the adoption of the optical limiter with the small limiting threshold value, a light path is simple, the manufacturing cost of the optical limiter is low, compared with an existing optical limiter, the limiting threshold value is reduced by about 50%, and the human eyes and optical precise instruments are more sensitively and efficiently protected from being damaged by the high power laser.