ABSTRACT The effects of carbon nanofibres (CNFs), titanium nanoparticles (Ti) and CNF–Ti fillers on the water absorption and mechanical properties of the composites were studied. The results showed that with the increase in filler mass fraction, the water absorption and mechanical properties of epoxy resin composites showed a trend of first increasing and then decreasing. When 6% CNF–Ti filler was added, the water absorption and diffusion coefficients of the composites were reduced to 2.32% and 1.04 ± 0.05 × 10−6 m2/s, and their tensile and impact strengths were improved by 200% and 124.55%, respectively, compared with the pure resin. However, when the filler was added in excess, agglomerates were generated inside the composite, which can affect the performance of the composite to a great extent. The above experimental results were verified by morphology observations via scanning electron microscopy.