The invention provides a thick-layer photoresist coating device, belongs to the technical field of photoetching and aims at solving the problem in the prior art that hundreds of microns of thick photoresist coating cannot be carried out. A bearing platform is provided with a first adjusting screw group; a first horizontal detector is arranged on the bearing platform; the bearing platform is provided with a linear guide rail pair; two guide rails are parallel; the linear guide rail pair is provided with guide rail slide sleeves respectively; the two guide rail slide sleeves are connected with a photoresist coating moving mechanism by two sets of height adjusting assemblies; a first push-pull rod is vertically mounted at the part which is 1/2 of the whole length of the photoresist coating moving mechanism; the other side of the first push-pull rod is connected by one side of a universal bearing; the first push-pull rod and a second first push-pull rod are arranged on the same straight line; the second first push-pull rod is connected with a linear motor moving body and a linear motor stator is fixed on the bearing platform; an optical base bearing platform is mounted between the linear guide rail pair and an optical base is arranged on the optical base bearing platform; a second adjusting screw group is mounted on the optical base bearing platform; and a second horizontal detector is arranged on the optical base bearing platform.