A novel linear cavity absorber for parabolic trough solar concentrator (PTC) was designed in the present study. The cavity absorber was used for conventional fabrication techniques and its thermal performance was carried out. The theoretical model of thermal efficiency for the cavity absorber has been established and verified by the experimental results. The results revealed that there was an agreement between the model and experiment. Furthermore, the temperature of the working fluid could reach 570 K, and the thermal efficiency of the cavity absorber was comparable to that of evacuated tube when the temperature of working fluid was in medium temperature. In conclusion, the thermal performance for the cavity absorber with glass cover and fins was improved. (C) 2014 Elsevier Ltd. All rights reserved.