The present invention relates to a clean plant cellulose extraction agent, a preparation method and applications thereof, and belongs to the field of biotechnology and agricultural product processingand production. The clean plant cellulose extraction agent is formed by mixing a liquid A and a liquid B, wherein a volume ratio of the liquid A to the liquid B is 3:1-5:1, the liquid A is an alkalineliquid, the liquid B comprises a crude enzyme liquid and an enzyme stabilizer, and Bacillus subtilis CGMCC1.836 is fermented, and bacterial separation is performed to obtain the clarified crude enzyme liquid. According to the present invention, the molecular structure of the colloid in the raw fiber is greatly changed by mainly using the alkaline pectin lyase, the alkaline polygalacturonase and the dilute alkali liquid, such that the stability of the colloid complex is severely damaged, and the alternating and circulating of swelling-modifying-colloid removing can be formed so as to achieve rapid hemp fiber degumming, reed pulping, cotton straw pulping and other purposes at the normal temperature.