Research on the application of nano-fluids into the direct absorption solar collector represents a prospective approach to solving the problem of high thermal losses of traditional solar collection systems. In this work, Au, CuS and Au-CuS blended Nanoparticles (NPs) were synthesized and the solar photo-thermal conversion performance of them was studied in an experimental investigation. According to the analysis of the results of the experiment, we knew that the temperature and photo-thermal conversion efficiency rised markedly as the light intensity and concentration increase. Our work found that mixing different NPs to match the solar spectral intensity can prepare working fluids for solar photo-thermal conversion instead of increasing the volume fraction of the same NP. When the concentration ratio of Au-CuS blended nanoparticles is 4:6, the conversion efficiency is the highest, reaching 26.04%.