We reported the influence of particle size (micro-B4C and nano-B4C) on microstructural evolution and mechanical properties in nanostructured Al matrix during heat treatment. The results indicated the incorporation of nano-B4C could significantly inhibit the grain growth of Al during heat treatment. The segregation layer in Al/B4C interface increased after heat treatment for all the composites samples. High density of Guinier-Preston (GP) zones and platelet could be observed in grain interior of all samples, while some coarse eta' phases (MgZn2) could be only detected in grain boundaries of AA7075 alloys and the composites with micro-6 4 C. The yield strength of the composites with the incorporation of nano-B4C could reach up to 958 +/- 28 MPa after heat treatment, which could be ascribed to the Hall-Petch strengthening and dislocation strengthening. (C) 2020 Elsevier B.V. All rights reserved.