The improved photocurrent of regioregular poly(3-hexylthiophene) (P3HT) and 6,6-phenyl C61-butyric acid methylester (PCBM) based polymer solar cells (PSCs) using LiF and Al cathode, modified with a reasonable thin Ag layer, was demonstrated. Using an optimal 4nm Ag layer-modified electrode gave 20% improved short-circuit photocurrent density over PSCs with only LiF/Al cathode under AM1.5G illumination of 100 mW·cm-2. The increased short-circuit photocurrent density is ascribed to plasmon enhancement of the polymer absorption by nanotextured Ag film. The fill factor and open voltage of PSCs using Ag/LiF/Al cathode are decreased compared with the control PSCs with only LiF/Al cathode, which result in the decrease in power conversion efficiency of PSCs modified with Ag film. The possible reason for the deteriorated performance of PSCs with Ag/LiF/Al is stronger carrier recombination at nanotextured Ag.