Two new a-aminophosphonate derivatives containing thieno[2,3-d]pyrimidine, diethyl(((6-ethyl-2-methyl-4-oxothieno[2,3-d]pyrimidin-3 (4H)-yl)amino)(4-methoxyphenyl)methyl) phosphonate (1) and diethyl((4-bromophenyl)((6-ethyl-2-methyl-4-oxothieno[2,3-d]pyrimidin-3 (4//)-yl)amino)methyl)phosphonate (2), have been synthesized by a facial phosphorylated reaction, and their structures were characterized by NMR, IR, HRMS and X-ray single-crystal diffraction. Compound 1 (C21H28N3O5PS, Mr = 465.49) belongs to the orthorhombic system, space group P212121, with a = 10.83653(16), b = 12.04906(19), c = 18.0061(3) A, V= 2351.06(6) A3, Z= 4, Dc= 1.315 g/cm3, p = 2.177 mm-1, F(000) = 984.0, the final R = 0.0389 and wR = 0.0985 for all data. Compound 2 (C20H25BrN304PS, Mr = 514.37) belongs to the orthorhombic system, space group P212121, with a = 10.9187(5), b = 11.9522(4), c = 17.7667(7) A, V= 2318.60(16) A3, Z = 4, Dc= 1.474 g/cm3,μ = 4.175 mm^-1, F(000) = 1056.0, the final R = 0.0367 and wR = 0.0946 for all data.