The fast-growing carbon sink grasses are new varieties developed through plant hybridization in some gramineous grasses. They have short growth period and high yield. The fiber morphology and chemical composition of five fast-growing carbon sink grass species were analyzed. Their feasibility to be used as pulping raw materials for the pulp and paper industry was also studied. The mixture of nitric acid and potassium chlorate was used to isolate grass fiber. Fiber length and width, wall thickness, and cell cavity diameter were determined using a biological microscope. Chemical components of the fast-growing carbon sink grasses were determined according to a relevant national standard. The results showed that all five fast-growing carbon sink grass species were suitable for using as pulping and papermaking raw materials. Of which, No.5 grass had the highest value in pulping and papermaking and its fiber length, the ratio of the wall to cavity, the ratio of length to width and the flexibility coefficient were 1.74 mm, 2.64, 123, and 28.51%, respectively. The contents of ash, benzene-alcohol extractive, lignin, pentosan, and cellulose in No.5 grass were 2.92%, 1.51%, 18.90%, 21.11%, and 43.82%, respectively.