The synthesis, culture of crystal and single-crystal X-ray crystallography of a new kind of polynitrostilbene ［1,4-di(2,4,6-trinitro-styryl)benzene, TNT-TTD］, which was synthesized through Knoevenagel Condensation by using piperidine as a base catalyst were reported. The crystal belongs to the Triclinic system with space group P-1.The compound was characterized by using FT-IR, ¹H NMR, ¹³C NMR and MS spectroscopy techniques. Density functional theory (DFT) B3LYP was employed to optimize structure and calculate frequencies of TNT-TTD. The calculated geometrical parameters were close to the corresponding experiments ones. The thermal decomposition of the title compound was investigated by DSC and TG-DTG methods at heating rate 10 ℃·min^-1. The melting point and initial decomposed temperature of TNT-TTD is 302 ℃ and 311 ℃. The results indicate that TNT-TTD has high heat resistant ability.