An apparatus for coating photoresist, comprising: a photoresist application unit and a gas supply unit configured to supply gas to the photoresist application unit; wherein the photoresist application unit comprises: a device cavity enclosed by sidewalls, a bottom plate and a cover plate, a rotation platform configured to carry a substrate and bring the substrate to rotate; a guide unit (206, 207, 209) conformal with the substrate, comprising a plurality of gas injection holes and a plurality of gas extraction holes, and a gas extraction unit configured to extract gas from the device cavity, characterized in that the guide unit is configured to uniformly blow the gas supplied by the gas supply unit over a surface of the substrate on which photoresist is to be coated and comprises the cover plate, and the plurality of gas injection holes is located at the center of the cover plate and configured to input the gas supplied by the gas supply unit into the device cavity therethrough, and the plurality of gas extraction holes is provided on a bottom plate of the photoresist application unit, and symmetrically arranged with a rotation axis of the rotation platform as a central axis. a photoresist application unit and a gas supply unit configured to supply gas to the photoresist application unit; wherein the photoresist application unit comprises: a device cavity enclosed by sidewalls, a bottom plate and a cover plate, a rotation platform configured to carry a substrate and bring the substrate to rotate; a guide unit (206, 207, 209) conformal with the substrate, comprising a plurality of gas injection holes and a plurality of gas extraction holes, and a gas extraction unit configured to extract gas from the device cavity, characterized in that the guide unit is configured to uniformly blow the gas supplied by the gas supply unit over a surface of the substrate on which photoresist is to be coated and comprises the cover plate, and the plurality of gas injection holes is located at the center of the cover plate and configured to input the gas supplied by the gas supply unit into the device cavity therethrough, and the plurality of gas extraction holes is provided on a bottom plate of the photoresist application unit, and symmetrically arranged with a rotation axis of the rotation platform as a central axis. a device cavity enclosed by sidewalls, a bottom plate and a cover plate, a rotation platform configured to carry a substrate and bring the substrate to rotate; a guide unit (206, 207, 209) conformal with the substrate, comprising a plurality of gas injection holes and a plurality of gas extraction holes, and a gas extraction unit configured to extract gas from the device cavity, characterized in that the guide unit is configured to uniformly blow the gas supplied by the gas supply unit over a surface of the substrate on which photoresist is to be coated and comprises the cover plate, and the plurality of gas injection holes is located at the center of the cover plate and configured to input the gas supplied by the gas supply unit into the device cavity therethrough, and the plurality of gas extraction holes is provided on a bottom plate of the photoresist application unit, and symmetrically arranged with a rotation axis of the rotation platform as a central axis.