The Major Disadvantage of Cement-Based Materials is their Brittle Nature Which is Attributed to their Poor Resistance to Crack Formation, the Low Tensile Strength, and Low Tensile Strain Capacities. Efforts Have Been Conducted to Enhance the Tensile Properties of Cement-Based Materials by Adding Micro Or/and Macro Fibers. Fibers Change Large Wide Cracks to Dense Microcracks. However, the Fibers Fail to Stop Cracking Initiation at Nanoscale and Propagation at Microscale. Extensive Research Endeavors over the Last Few Years Demonstrated the Application Potential of Various 1D Nanomaterials, Mainly Carbon Nanofiber and Carbon Nanotube (CNT), in Cementitious Composites. Compared with 0D Nanomaterials, 1D Nanomaterials Can Effectively Restrict the Formation and Growth of Nanocracks in Cementitious Composites, Which Benefits the Development of High Crack-Resistant Cement-Based Materials with Superior Mechanical Properties and Durability. This Chapter Reviews Recent Research on Design, Performance, and Mechanism of Cement-Based Materials with 1D Nanomaterials.