In this work, the fatigue properties of in-situ TiB2 particle-reinforced 7050 Al-matrix (TiB2/7050Al) composites at room temperature (RM), 100 ℃ and 150 ℃ were studied, respectively, and the microstructure changes, fatigue fracture characteristics and fracture mechanism were analyzed. The results indicate that when the fatigue temperature increased, the amount of S phase precipitation along grain boundaries increases, forming a banded distribution with TiB2 particles near the grain boundary regions. The RM fatigue limit of the composite is high up to 307.5 MPa. Under the same fatigue strength, TiB2/7050 composites can withstand fatigue cycles far greater than 7050Al alloy. With the increase of temperature, the fatigue performance of the composite gradually decreased, and unlike at RM and 100 ℃, the use of Weibull three-parameter model is necessary to obtain a satisfactory S-N curve at 150 ℃. In some locations of the steady-state crack propagation stage, the direction and spacing of fatigue striations were influenced by grain orientation, grain boundaries and TiB2 particle bands. Therefore, the effects of TiB2 particles, grain boundaries, and precipitations on the fatigue processes were analyzed to reveal the strengthening mechanisms of the composite.