The invention relates to a selective hydrogenation method of trace acetylene in a device using methanol to prepare olefin.The selective hydrogenation method is characterized in that the C2 material from the top of a dethanizer in the device using methanol to prepare olefin is allowed to enter a thermal-insulation bed reactor to perform selective hydrogenation; Pd-Pb catalyst is loaded into the thermal-insulation bed reactor, Al2O3 or the mixture of Al2O3 and other oxides is used as the carrier, the catalyst combines with hydroxyl-bipyridine through the carrier during preparation, and the hydroxyl bipyridine combined to the carrier and active components form metal complex; the reaction condition includes: the inlet temperature of the thermal-insulation bed reactor is 25-60 DEG C, reaction pressure is 1.5-2.5MPa, and air speed is 2000-10000h<-1>.When the method is used to perform the selective hydrogenation reaction, the reaction activity and selectivity of the catalyst are increased evidently, and the stability of the catalyst is enhanced; when the hydrogenation raw material contains a certain amount C4 fraction, the catalyst also has excellent hydrogenation performance.