Abstract: Nanofluids, as an emerging heat and mass transfer medium, exhibit broad application potential in engineering and biomedical fields. The regulation of effective physical properties is a key research issue. The study integrates experimental data, theoretical models, and empirical correlations to systematically examine the impact of particle size on the effective thermal conductivity, viscosity, and electrical conductivity of nanofluids. Additionally, it investigates the influence of particle volume fraction and temperature on these properties. Research illustrates that different effective physical properties respond significantly differently to particle size. The effective thermal conductivity is influenced by a combination of factors including interface scattering, interfacial thermal resistance, and Brownian motion, exhibiting an optimal particle size. The viscosity shows some discrepancies in its trend with particle size due to the complexity of particle interface effect.