Some 50 metal-containing polyimides with the metallic elements (Mg, Ca, Sr, Ba, Pb, Co, Ni) in the main chain were prepared first by reacting pyromellitic dianhydride (PMDA) with the mixture of divalent metal salts of p-aminobenzoic acid [ABA(M)] and 4, 4’-diaminodiphenylmethane (MDA) to form polyamic acid salts, and then the desired polyimides were obtained in high yield by separating the polyamic acid salts from the solvent and heating them under the imidization conditions. The structures of the samples were characterized by H-1-NMR and IR, and the thermal properties of polyimides were measured by TG-DTA. It was found that the thermooxidative stability of polyimides decreased as a small amount of a metal element was introduced, and the stability of polymer varied slightly or tends to constancy as the metal content increased to a certain degree. In addition, the inherent viscosity of the polyamic acid salt solutions also decreased markedly with the increase of the metal content.