A method for making a CMOS device includes: providing a substrate with a semiconductor layer and a photoresist layer; irradiating the photoresist layer through a mask to obtain a first photoresist and a second photoresist having a height smaller than that of the first photoresist; first implanting ions to the semiconductor layer; ashing the first and second photoresists to expose a first region of the semiconductor layer and removing the second photoresist to expose a second region of the semiconductor layer; secondly implanting ions to the semiconductor layer; removing the first photoresist to expose a third region of the semiconductor layer surrounded by the second region; forming a third photoresist and a fourth photoresist on the semiconductor layer; etching the semiconductor layer to remove the semiconductor layer not covered by the third and fourth photoresists; removing the third and fourth photoresists; and thirdly implanting ions to the semiconductor layer.