The synthesis of 4-hydroxy-3-methoxyphenyl-oxime has been made from vanillin, hydroxylamine hydrochloric acid and sodium hydroxide The factors of reaction process include theses,such as temprature, reagents, strong bases and mole rate of three crude materials.The results show that the best mole rate of three reagents is for 1:1.2:1.1,and the product ratio is for 97.4%The reactive process and mechanism of synthesis has been discussed.The synthesis product has been corroborated after the measurement of melting point and analysis of its IR,¹HNMR,TIC-MS.