The solar cells based on different solvent blends of poly(3-hexylthiophene) (P3HT) and -phenyl C61-butyric acid methyl ester (PCBM) as acceptors are fabricated. are analyzed by UV-vis absorption spectroscopy and photoluminescence (PL) spectroscopy. The results show that high boiling point solvent leads to an enhanced P3HT ordering in the P3HT:PCBM blend system, and causes an increased incident light absorption and PL spectrum, which contributes to the enhancement of device performance. After 130 ℃ thermal annealing, The UV-Vis absorption, PL spectrum and the performance of the device are further enhanced. The performance of the device prepared with low boiling point chloroform solvent increases obviously after thermal annealing. The solar cell prepared with chlorobenzene solvent after 130 ℃ thermal annealing achieves an open circuit voltage(Voc)of 0.57 V, short circuit current density(Isc)of 8.74 mA/cm2, fill factor (FF ) of 59.2% and power conversion efficiency (PCE) of 2.95% under 100 mW/cm2 air-mass 1.5 solar simulator illumination.