A novel asymmetric bis(thioether anhydride), 3,4′-PTPKDA, was synthesized by four steps. Based on 3,4′-PTPKDA and two other symmetric dianhydride isomers, 3,3′-PTPKDA and 4,4′-PTPKDA, a series of isomeric polyimides was prepared by a conventional two-step method. The glass transition temperature followed the decreasing order of the polyimides based on 3,3′-PTPKDA, 3,4′-PTPKDA, and 4,4′-PTPKDA. 3,3′-PTPKDA- and 3,4′-PTPKDA-based polyimides showed improved solubility compared with 4,4′-PTPKDA. The polyimide resin 3,3′-PTPKDA/4,4′-oxydianiline/phthalic anhydride exhibited better rheological properties and melt stability than the other two isomers.