This paper presents the micromechanical modeling of fiber bridging constitutive law of a discontinuous fiber reinforced composite (DFRC) under cyclic loading. Fiist, the derivation of fiber bridging constitutive law under monotonic loading is briefly reviewed to highlighthe approach to obtain the bridging stress carried by randomly distributed discontinuous fibers. Second, the relation between single fiber pa-out/push-in load amplitude and crack opening displacement amplitude under cyclic loading is derived. Third, fiber bridging constitutive l aw under cyclic loading is derived and obtained in two ways: numerically and analytically. Finally, the fiber bridging constitutive law is compared with experimental data of a cyclically loaded fiber reinforced concrete (FRC), and its validity is shown.