In the presence of electrocrystallization catalyst modified by Zr, Zn, K, P and haloane, 1,2-propylene glycol is air-oxidated to produce 40% pyroracemic aldehyde product by one-step. Said oxidation reaction is implemented in a fixed-bed adiabatic reactor, and the reaction resultant is quenched. Said modification method of the catalyst is characterized by that the metal elements of Zr, Zn and K are used to make impregnating modification, and the P and haloane are used to make steam-introducing modification. Its reaction temp. is 450-650 deg.C, the conversion rate of 1,2-propylene glycol is up to 100%, and the selectivity of pyroracemic aldehyde is up to 75%.