Solar concentrators are an important facility to utilize the solar energy. There are many kinds of solar concentrators. In this work an experimental has been implemented to improve the thermal performance of Parabolic Trough Solar Collector (PTSC) using three different fluids as a working fluid (water, nanoparticles of CuO mixed with distilled water nanoparticles of Al 2 O 3 mixed with distilled water) with concentration ratio 0.01% and mass flow rate 20Lt/hr without tracking system. The experimental tests have been carried out in electro-mechanical engineering department at university of technology in Baghdad city during October 2017 and daytime between (9am -15pm) hours. The obtained results for three different fluids are as follows:-Using (CuO + distilled water) as a working fluid increases the average of the output temperatures by 10.4%, the average of useful heat gains increases by 11% and the average of the collector efficiencies increases by15%.-Using (Al 2 O 3 +distilled water) as a working fluid increased the average of output temperatures by 4%, the average of useful heat gains is increased by 6.5% and the average of collector efficiencies is increased by 8.2%.