The flow stress behavior of the nanometric Al2O3 particulate reinforced Al alloy matrix composites were investigated in the temperature range from 360 to 480°C, with strain rates of 0.001–1s−1 on Gleeble-1500 machine. The results show that the flow stress increases with increasing strain rate and decreasing temperature. The flow stress of this deformed composites shows a dynamic recovery character in the temperature range from 360 to 440°C and in the strain rate range of 0.001–0.01s−1, while that deformed at 480°C shows dynamic recrystallization character. The processing map at the strain of 0.4 is obtained and exhibits three safe deformation domains: 360–400°C at 0.001–0.01s−1, 400–440°C at 0.001–1s−1, and 440–480°C at 0.001–0.01s−1. According to the processing map and microstructure observation, the optimum hot-working parameters are determined to be 480°C/0.001s−1.