In this article, we report a facile, direct synthesis route to prepare CdSe/P3HT nanocomposites with CdO used as cadmium source, Se powder as selenium source, liquid paraffin and oleic acid as solvents, P3HT as a conjugated polymer template. The effect of the reaction temperature as well as the Cd:Se molar ratio on the morphology and photovoltaic property of CdSe/P3HT nanocomposites was studied. The results show that the shape and the degree of aggregation of CdSe nanocrystals are not only temperature-dependent, but also heavily influenced by the Cd:Se ratio, changing from dot-shaped to tetrapod-shaped, and from homo-dispersed to seriously aggregative. The UV–vis absorption spectra of CdSe-P3HT show a broader range and higher intensity of absorption than that of pure P3HT. The improved PL quenching in PL spectra of CdSe-P3HT indicates charge transfer between CdSe nanocrystals and P3HT.