The invention discloses a method for preparing 1,4-butanediol by two-part hydrogenation of maleic acid dialkyl ester, comprising the following steps: (A) connecting a first hydrogenation section and a second hydrogenation section in series; (B) providing raw material containing maleic acid dialkyl ester for the first hydrogenation section; (C) contacting the maleic acid dialkyl ester raw materialwith hydrogen and catalyst at the first hydrogenation section to produce a product which is mainly 1,4-butanediol and contains at least one of gamma-butyrolactone, tetrahydrofuran and succinic acid dialkyl ester; (D) arranging condensation and recycling separation equipment between two the hydrogenation sections; (E) providing the product of the first hydrogenation section to the second hydrogenation section to serve as raw material by cooling separation; (F) after the unreacted hydrogen of the first hydrogenation section is separated from liquid, putting parts circularly into the first hydrogenation section, and putting parts circularly into the second hydrogenation section; and (G) contacting the product of the first hydrogenation section with the hydrogen and the catalyst at the secondhydrogenation section to produce 1,4-butanediol, and a product containing at least one of the gamma-butyrolactone and the tetrahydrofuran.