Fiber reinforced polymer (FRP) reinforced ultra-high-performance concrete (UHPC) structural elements have become increasing popular in research and industry communities. In this paper, uniaxial tension tests were conducted to study the effects of fiber type, fiber length, and fiber content on tensile behavior of FRP grid reinforced UHPC plates (FGRUPs). Additionally, the microstructure analysis of specimens was conducted using scanning electron microscopy. Test results reveal that carbon FRP (CFRP) grid can substantially enhance the tensile performance of UHPC under tension: (1) the FGRUPs exhibit a post-crack strain-hardening behavior while the UHPC plates exhibit a post-crack strain-softening behavior; (2) the FRP grid enhances the cracking stress of UHPC specimens (except for plates with 1% basalt fibers) and the stiffness of the second segment of the stress–strain curve, and substantially enhances the ultimate tensile stress UHPC specimens. Also, the cost-effectiveness analysis indicates that plates containing 1% of 12 mm length PE fibers have a highest cost efficiency index. Finally, a modified tensile stress–strain model for FGRUPs is proposed and verified.