This study presents the design and performance evaluation of a novel concentration photovoltaic/thermal (PV/thermal) system based on parabolic trough concentrator and indium tin oxide-ethylene glycol (ITOEG) nanofluid spectral filter. The overall design principle of the PV/thermal system is introduced, and the ITOEG nanofluid spectral filter is prepared and experimentally tested. For the full spectrum, the average transmittance and absorbance of the nanofluid spectral filter are 69.1% and 30.9%. The optical behaviour evaluation results reveal a double-peak radiation flux density distribution on the nanofluid channel bottom surface as well as on the solar cell module surface. When the north-south sun-tracking error increases to 0.2°, the optical efficiency of the PV/thermal system decreases to 93.7%. That means the system has a relatively good adaptability to the sun-tracking error. The thermodynamic analysis results reveal that the theoretical photoelectric conversion and solar thermal efficiencies of the PV/thermal system are 29.1% and 17.2%. The thermal efficiency of the PV/thermal system can be increased by increasing the nanofluid inlet flow velocity or by decreasing the nanofluid inlet temperature properly.