Nitration of 4,4-biphenyldicarboxylic acid (BPDC) was studied and an aromatic carboxylic acid containing four nitro groups was synthesized and characterized through elemental analysis and IR spectra. Crystal structure of TNBPDC (TNBPDC = 2,2,6,6-tetranitro-4,4-biphenyl dicarboxylic acid) was determined by X-ray single-crystal diffraction. The title compound (C20H20N6O14, Mr= 600.42) crystallizes in tetragonal, space group I41/a with a = 9.8774(1), b =9.8774(1), c = 25.335(7) (A), V= 2471.7(8) (A)3, Z = 4, Dc = 1.613 g/cm3, F(000) = 1240, μ(MoKa) =0.142 mm-1, T= 294(2) K, the final R = 0.0797 and wR = 0.2177 for 554 observed reflections with I ＞ 2σ(Ⅰ). In this crystal, there exist a number of H-bonds which link the molecules to form a three-dimensional infinite network structure. The thermal decomposition of the title compound has been carried out through DSC and TG-DTG analyses at a heating rate of 10 ℃/min. The results indicate that the compound has high heat-resistant stability.