The invention discloses a high extinction ratio pulse output optical fiber Raman random laser based on polarization modulation and relates to the field of a pulse fiber laser. The pulse output optical fiber Raman random laser comprises a pump laser, polarizers, polarization controllers, an optical fiber, a circulator, a polarization switch and a drive thereof. Pumping of polarized light is realized through the polarizers; by adding the polarizer and the polarization switch in a ring reflector formed by the circulator, the polarization state of the Stokes light can be modulated; and due to polarization correlation characteristics of Raman gain, modulation of laser output power can be realized, and high extinction ratio pulse random laser output can be obtained. By utilizing the polarization property of the fiber random laser and by adopting a new polarization modulation mode, high extinction ratio pulse output random laser is realized; and the repetition frequency of the pulse is decided by the driving signal of the polarization switch.