The perovskite La1-xSrxMnO3 nano thin-film on the slide glass basis were prepared by sol-gel method and dip-coating technology. The heat decomposition of the precursor gel was analyzed by means of TG/DTA. The appearance characteristic of the thin film was observed by AFM. The phase change was analyzed by XRD and crystal grain size was also calculated. The results show that the perovskite La1-xSrxMnO3 thin film can be synthesized at 600 °C and average crystal grain size is 10.349 nm. The degradation experiment of various water-soluble dyestuffs was performed using the film as photo-catalyst. The results reveal that this nano thin-film with Sr doping has good photo-catalysis and when x=0.2 the effect is best.