Provided are a CMOS circuit structure, a preparation method thereof and a display device, wherein a PMOS region in the CMOS circuit structure is of a LTPS TFT structure, that is, the PMOS semiconductor layer is prepared from a P type doped polysilicon material; an NMOS region is of an Oxide TFT structure, that is, the NMOS semiconductor layer is made of an oxide material; three doping processes applied to the NMOS region during the LTPS process may be omitted in the case in which the NMOS semiconductor layer in the NMOS region is made of an oxide material instead of the polysilicon material, which may simplify the preparation of the CMOS circuit structure as well as reduce a production cost. Furthermore, it is only required to crystallizing the PMOS semiconductor layer, which may also extend the lifespan of laser tube, contributing to reduction of the production cost.