Microorganism is a variety of different types of organisms, it is monomer or cluster cells, it can carry out its own growth alone, generating energy and self-propagation. Now,the four common micros of the paper machines:bacterium, fungi, algae, protozoa. Riching with a large number of nutrients in the paper machine system,which is suitable for microbial growth, plus appropriate temperature and adequate water, microorganisms can breed rapidly in such a system.Alkaline paper-making system environment is conducive to bacterial growth. Acid paper-making environment is conducive to mold growth. The sticky excrement from the growing microorganisms is very easy to adhere on the inner wall of the slurry flowing pipeline and the equipment surface, and then producing bacterial mud and filling material, slurry admixture is also easy to corrupt and generate slime pulp.These slime pulp sediments cause many negative effects on the production of paper-making machine and the quality of products. The harm of Microorganism in Paper Machine System: Cause the increase of paper breaking, the output lost and the decrease of running efficiency. Generate pulp scar, hole and so on are produced, which reduces the quality of the finished paper . Pulp and additives produce discoloration and deterioration, which affect the normal operation of paper machine and the effect of additives . Equipment corroded and damaged. The paper machine system produces peculiar smell.