In this invention, oxime is used as raw material being hydrolyzed in acid solution. Said hydrolytic process is coupled with osmotic vaporization membrane separation technique. The produced organic by-product ketone is removed by said membrane directionally and high efficiently. Thus recovers the limitation of the reaction chemical equilibrium of the hydrolysis, proceeding the reaction to the direction of production of hydroxylamine salts. This technique enhances the conversion rate greatly with high yield of hydroxylamine salts. This inventive method is better than prior art method with advantages of: simple process, less kinds of raw materials being needed, easy to operation, no side reaction, mild reaction condition and high yield of hydroxylamine salts being up to 80%.