A single crystal of energetic compound 4-amino-1,2,4-triazolium picrate (4-ATPA) was cultured from methanol solvent at 25 ℃. The compound crystallized in the orthorhombic system, is space group Pcnb with a=9.177(4)， b=13.279(6)，c=19.855(6) ?, V=2419.5(16) ? 3, Dc=1.720 g·cm-3, Z＝8, μ(MoKα)=0.152 mm-1 and F（000）=1280. Of the 2580 total reflections, 2194 were unique(Rint=0.0048). The final R=0.0588 and wR=0.1370 for 2194 observed reflections with I>2σ(I). Single X-ray diffraction reveals that the structure is composed of 4-amino-1,2,4-triazolium cation and picric anion.