The monolithic series interconnection of flexible thin film solar cell on polymer(PI) substrate is obtained by laser etching and other technology,and laser etching of compound back reflector(Ag/ZnO) on polyimide is very important.The optical characteristics of polyimide and Ag/ZnO are analyzed.Pulsed lasers with wavelengths of 532 nm and 1 064 nm are used for comparison.The influence of various laser parameters like laser power,pulse overlap,etc.,is discussed and the parameters are optimized.Laser-etching mechanism is analyzed.The experiments show that 1 064 nm pulse laser is more suitable for laser etching of Ag/ZnO on PI.At laser power of 860 mW,etching speed of 800 mm/s and repetition frequency of 50 kHz,a very good etching line with 32 μm width is obtained.