Abstract: Pressurizer vertical support anchor frames in nuclear power plants with pressurized water reactors are primary embedded part. Deviation occurs often during the installing process. It is difficult to evaluate the displacement deviation impact on the follow-up installation of pressurizer, for its complicated structure. This paper analyzed the adjustable margin of the vertical supports of the pressurizer. The optimal installation position of the pressurizer is determined by simulation numerical calculation, based on the actual deviation conditions of pressurizer vertical support anchor frames, and considering  the installation requirements of the pressurizer. In order to reduce the difficulty of pressurizer installation on site, this paper put forward the optimization recommendation about the support structure based on the structure characteristics of the pressurizer as follows: increasing the diameter dimension of the lower plate sleeve holes to increase the adjustable margin of lower plate, using the flat washer instead of the spherical washer to relax the perpendicularity requirements of the anchor bolts installation.