The mechanical properties of dental composites were improved by porous diatomite and nano-sized silica (OX-50) used as co-fillers.The resin composites,filled with silanized OX-50 and silanized diatomite (40:60 wt/wt),presented the best flexural strength (133.1 MPa),elastic modulus (9.5 GPa) and Vickers microhardness (104.0 HV).Besides these,TiO2 nanoparticles were introduced to tune the dental resin composites colours which were valued by the CIE-Lab system.The colour parameters (L*,a*,b*) showed that the colour changes of resin composites could be perceived obviously,when 300-400 nm TiO2 particles were introduced as fillers.The resin composite,filled with 0.5 wt％ TiO2,exhibited both clear discolouration (△E*=3.22) and high mechanical strength.Using scanning electron microscope (SEM) equipped with an energy dispersive X-ray (EDX),the titanium elemental mapping results indicated that the TiO2 particles were distributed evenly in the prepared dental composites.