The ionic liquids (ILs) as heat transfer fluids (HTFs) are limited for lack of strong ability in absorption of sunlight. Hence, nanoparticles are added in pure ILs to improve their thermal and optical properties. In this study, a highly stable ionic liquid nanofluid (Ionanofiuid) was first prepared by dispersing SiC nanoparticles in [HMIM]BF4 and their thermophysical and optical properties were thoroughly investigated as HTFs application in direct absorption solar collectors (DACs). An enhancement in thermal properties in Ionanofluids was observed. 0.06 wt% SiC Ionanofluids could increase the TC and specific heat of pure [HMIM]BF4 about 10.2% and 5% at 25 degrees C, respectively. With the increase of temperature, the thermal properties increase, while the viscosity and density decreased. It was indicated that SiC Ionanofluids were more suitable in Medium-high temperature application. Additionally the results of optical properties showed that SiC Ionanofluids were a superior solar absorption material, where the extinction coefficient of 0.03 wt% SiC Ionanofluids could increase about 5.8 cm(-1). In summary, the advantageous performance ensured the potential of SiC Ionanofluids as advanced HTFs in solar energy system. We believed that this information have guide meaning to the practical design of DAC system.