TiO_{2nanoparticles} (NPs) were synthesized via solution-gelation (sol -gel) method. Polymer photovoltaic cells with structure of ITO/PEDOT:PSS/P3HT:PCBM/TiO₂/Al w ere fabricated.Effects of different TiO₂NPs annealing temperatures and dispersing solvents on the optical properties,morphological structure and electrical properties are invest igated,and then the effects of those on the performance of the solar cells are also investigated.The experiment al results show that the power conversion efficiency (PCE) reaches 2.52% when the thermal annealing tempe r ature is 80℃.Compared with the control device,the power conversion efficiency (PCE) and fill factor (FF) of the devi ce are enhanced by 60% and 64.7%,respectively.