3,4-dinitropyrazole (DNP) was synthesized by N-nitration, thermal rearrangement and C-nitration with pyrazole as the raw material. A pure DNP single crystal was obtained by solvent evaporation using water as a solvent, and its structure was characterized by X-ray single crystal diffraction. The results showed that the single crystal structure of DNP contained water, and the molar ratio of DNP/water was 4:1. The DNP molecules existed stably due to the presence of intermolecular and intramolecular hydrogen bonding, as well as pi-pi stacking between DNP molecules. This study was valuable to the production and application of DNP.