Polymer solar cells have been attracted attention because they combine flexibility with low-cost fabrication, have been previously developed based on bulk-heterojunction. Many research groups have developed solar cells based on Poly (P3HT) and (PCBM) composites. The nanostructure morphology of P3HT: PCBM composites play an important role for affecting the device performance. Many researches propose a lot of method to improve the morphology, such as the selection of solvent in photoactive layer and the thermal annealing effect. In this research we have studied the nanostructure morphology of P3HT: PCBM composites film by blending with Cetrimoniumbromide (CTAB). We have prepared Polymer solar cells incorporating an active layer of P3HT: PCBM blended with CTAB. The short-circuit current density of the polymer solar cells improved after blend if 0.01wt% of the CTAB into P3HT: PCBM active later. The device structure of ITO/PEDOT: PSS/P3HT: PCBM: CTAB/Al was measured under AM 1.5G 100 Mw/cm2 illumination, exhibited a power conversion efficiency of 2.5%, which is a 17% improvement than the standard device. The power conversion efficiency increased from 2.13% to 2.5%. The short current density increased from 5.47mA/cm2 to 6.43mA/cm2.