The Pd-catalyzed cross-coupling polycondensation of 2,6-dibromoaniline or 2,6-dibromo-4-tert-butylaniline with 1,3-phenylenebis(trimethylene boronate) in benzene-water in the presence of K2CO3 and Bu4NCl gave poly(1,3-phenylene-2-amino-1,3-phenylene)s in 56-86% yields. The number average molecular weights of the poly(1,3-phenylene)s determined by GPC using styrene standards are 2500-5720, which correspond to the degree of polymerization of 15.0-25.6. The thermal stabilities of the polyphenylenes were evaluated by thermalgravimetry. The corresponding dimer and tetramer model compounds of poly(1,3-phenylene-2-amino-1,3-phenylene)s were prepared, and their properties were compared with those of the poly(1,3-phenylene)s.