This invention discloses a method for preparing phenolic hydroxyl-containing polyimide adhesive. The method comprises: (1) reacting phenolic hydroxyl-containing aromatic diamine, or its mixture with other aromatic diamines, with aromatic dianhydride at a mol ratio of 1:1 in strongly polar non-proton organic solvent at 0-10 deg.C for 4-8 h to obtain uniform, transparent and viscose polyhydroxyamic acid solution; (2) adding azeotropic dehydrator in nitrogen atmosphere, heating, performing imidization reaction under refluxing and dehydration at 120-160 deg.C for 1-6 h, and cooling to room temperature to obtain phenolic hydroxyl-containing polyimide adhesive. The volume ratio of azeotropic dehydrator to strongly polar non-proton organic solvent is 1 :( 1-5). The method has such advantages as easy operation, no special requirement for equipment, and high product quality. The phenolic hydroxyl-containing polyimide adhesive has such advantages as short adhesion and curing time, low energy consumption, and high adhesiveness to copper foil and polyimide thin film, and can be used to produce bi-layer flexible printed circuit boards.