Abstract: The influences of heat, wet, and plasma treatments on mechanical properties of UHMWPE fibers under normal environmental conditions were studied, and the rules and mechanism of the influences were preliminarily discussed. The results show that the tensile strength of UHMWPE fibers decreases considerable after heat treatment, while breaking elongation increases slightly with rising temperature of heat treatment. The duration of wet treatment has no prominent influence on the mechanical properties of the fibers and the tensile strength decreases with rising temperature of wet treatment. Plasma treatment results in some pickling on the surface of the fibers and their tensile strength and breaking elongation decrease.