The invention discloses a method for adjusting the catalytic performance of a perovskite type oxide La0. 4Sr0. 6Co0. 8Ni0. 2O3 by utilizing a pH value. The preparation method comprises the following steps: preparing a perovskite type oxide La0. 4Sr0. 6Co0. 8Ni0. 2O3 by a sol-gel method; weighing each metal salt according to the total molar weight of 0.002 mol, putting the metal salt into a 100mL beaker, weighing citric acid monohydrate which is 1.5 times of the total molar weight of the metal salt, putting the citric acid monohydrate into the beaker, adding distilled water, and stirring for dissolving; adjusting the pH values of the solutions to be 3, 5, 7 and 9 respectively by using ammonia water, keeping one part of the solution without adjusting the pH value, and measuring the pH valueto be 1.6; putting all the solutions into a magnetic stirrer for water bath heating and evaporation to dryness, wherein the water bath temperature is 85 DEG C, and the rotating speed is 10r/min; drying the solution at 120 DEG C for 12 hours when the solution becomes gel; putting the mixture into a muffle furnace and calcining at 350 DEG C for 30 minutes, wherein the heating rate is 10 DEG C/min; after calcining, taking out the mixture for grinding, putting the mixture into the muffle furnace again, and calcining for 180 minutes at 800 DEG C; and when the temperature in the furnace is reduced to room temperature, taking out and grinding the mixture to obtain the perovskite oxide with the corresponding pH value.