<p>A yield strength model is developed for the TiB₂ nanoparticle (NP) reinforced precipitate-hardened aluminum (Al) matrix (TiB₂/Al–Zn–Mg–Cu) composites based on microstructure characterization. According to the performance of alloy and counterpart composites with different particle additions (1, 3, 5 wt pct) and established model, the strength increments caused by reinforced particles and precipitates were quantified. The calculated results indicate that NPs addition may deteriorate to the strengthening contribution by precipitates. In particular, the negative influence of NPs on the strength increment caused by matrix precipitates should be attributed to the formation of interface precipitates at NP/Al interface and coarse MPs near dislocations pinned by NPs. The present work paves a way to understand the strengthening mechanisms in multi-phase strengthened alloys/composites.</p>