A method for producing a cross-linked polyvinyl alcohol separator having a film of cross-linked polyvinyl alcohol for an alkali-zinc secondary battery, and a cross-linked polyvinyl alcohol separator produced by the method are disclosed. The method includes the steps of:(1) providing a film of polyvinyl alcohol having degree of saponification of 70 to 98.5% and containing 1,2-diol units;(2) contacting the film of polyvinyl alcohol with an oxidizing agent to effect oxidative cleavage of the 1,2-diol units;(3) contacting the film of polyvinyl alcohol with an acid catalyst to catalyze acetalization to form a film of cross-linked polyvinyl alcohol; and(4) preparing a separator with the film of cross-linked polyvinyl alcohol.