An organic electroluminescent device and its manufacturing method, and a display device are provided. The manufacturing method of the organic electroluminescent device includes: forming a first electrode on a predetermined region of an insulating base; conducting a surface treatment to an upper surface of the first electrode and an upper surface of the insulating base which is not covered by the first electrode, so that the upper surface of the first electrode is lyophilic and the upper surface of the insulating base which is not covered by the first electrode is lyophobic; forming an electroluminescent layer on the first electrode; and forming a second electrode on the electroluminescent layer. In the organic electroluminescent device formed by the manufacturing method, the electroluminescent layer has a relatively uniform thickness.