The crystal of picric acid is obtained by the method of evaporation. It is characterized by using element analysis and FTIR. The crystal structure of PA is determined by single crystal diffraction analy- sis. The crystal is orthorhombic. Its space group is Pca2 (1) with crystal parameters of a = 0. 926 84(16)nm ,b = 1.913 9(4) nm,c =0. 971 6(2) nm,V = 1. 723 6(6)nm³ ,Z =4,D_c, = 1.766 g . CIII ^-3．μ = 1. 66 cm ^-1,F (OOO) = 928. The final R is 0. 045 4,R_w ,0. 097 9。