The invention relates to tert-butyl salicylaldoxime and a synthetic method thereof. The method comprises the following synthetic steps: mixing 30mL of methanol and 20mL of methylbenzene, transferring the mixture into a three-necked bottle, heating to a reflux state, and then adding 0.58g of metal magnesium until the metal magnesium is completely dissolved; adding 6.01g of p-tert-butyl phenol, continuously reacting for 90 minutes, distilling off a methanol-methylbenzene azeotrope at the temperature of 80-85 DEG C, adding 5mL of methylbenzene every two minutes in the process, and adding twice; adding 2.76g of paraformaldehyde, controlling the temperature to be 100-110 DEG C, reacting for 120 minutes, adding 5mL of methylbenzene every two minutes in the process, and adding for three times; raising the temperature to be 120-125 DEG C, distilling off the methylbenzene, reducing the temperature to be between 45 DEG C and 47 DEG C, slowly dripping an aqueous solution of hydroxylamine hydrochloride, and controlling the time to be 180 minutes; and finally, acidifying the product, performing reduced pressure distillation and petroleum ether cleaning, thereby obtaining a target product, wherein the actual yield and purity are respectively 93.12 percent and 97.51 percent.