Compared the most reported synthesis methods, a series of LaxSm1-xMn2O5 (x = 0, 0.1, 0.3, 0.5) catalysts were first synthesized through sol-gel solution combustion synthesis with a short cycle and high yield. The main impact of different La/Sm molar ratios is the amount of surface adsorbed oxygen (O-ads) and surface Mn4+ ions as revealed by XPS results. Electrochemical properties are characterized by rotating disk electrode (RDE) and the full dischargeable Al-air battery with 4 M NaOH electrolyte. The measurements of RDE reveal that the electron transfer number of LaxSm1-xMn2O5 (x = 0, 0.1, 0.3, 0.5) are all closed to 4, and the sample prepared with x = 0.1 possesses the most excellent electrocatalytic activity for oxygen reduction reaction (ORR) and good discharge performance in alkaline medium. All of the above results indicate that the LaxSm1-xMn2O5 (x = 0, 0.1, 0.3, 0.5) are promising catalysts with a high catalytic activity toward ORR.