Abstract: The applicabilities of two high-strength synthetic fibers for engineered fiber/cement composites were researched, with hydrophilic aramid fiber and hydrophobic ultra-high molecular weight polyethylene (UHMWPE) fiber. The results show that engineered aramid fiber/cement composites have no strain-hardening ability and present single crack failure pattern under uniaxial tensile load, and engineered UHMWPE fiber/cement composites show strain-hardening ability and multi cracking pattern. The UHMWPE fiber is more suitable for fiber/cement producing compared with aramid fiber. With the decrease of matrix water-to-binder ratio, the tensile strength of engineered UHMWPE fiber/cement composites increases but the strain-hardening ability decreases. It is suggested that when producing engineered UHMWPE fiber/cement composites, coordination of fiber tensile strength and fiber-matrix bond strength should be considered.