Abstract: To examine the strength and deformation properties of synthetic cotton fibers reinforced soil, an experiment is conducted to measure its unconfined compressive strength with six different fiber contents (0.5%, 1.0%, 1.5%, 2.0%, 2.5% and 3.0% by weight), four different fiber lengths (1.25, 2.50, 3.75 and 5.00 cm), and three different patterns of fiber distribution (random distribution, layered cross distribution and layered one-way distribution). Results show that as both fiber content and fiber length increases, the compressive strength is increased first and then decreased, with a peak strength in the condition of fiber content of 1.0% and fiber length of 2.50 cm. Under this optimum condition, the strength is increased by 24.8% when the reinforcing fibers are added in the pattern of random distribution and decreased by 15.1% when added in layered one-way distribution, while it remains nearly the same if the fibers in layered cross distribution. The stress strain characteristics of the reinforced soil are strain hardening. With both fiber content and fiber length increasing, its average deformation modulus is increased first and then decreased, varying in the range of 0.56 - 1.26 MPa. This experiment demonstrates that the reinforcing fibers will help restraining soil radial displacement and increasing soil strength if certain reasonable and practical means can be used to control their distribution patterns so as to keep them oriented along the local tensile stress.