In order to simplify the process, nitroguanidine(NQ) was synthesized from crystallization mother liquor with the nitrate method by controlling crystallization, the average grain size, acidity and purity of the product met the military requirements according to experimental results. The optimum process conditions were obtained as follows: the stirring rate: 350r/min; the dropping speed of dilution solution: 2mL/min; the crystallization temperature: 271K; the time for crystal growing:90 minutes. The results show that NQ with average grain size between 3μm to 6μm, acidity below 0.05% and purity exceed 99.2% could be produced in the optimum conditions. The crystal morphology of controlling crystallize product was compared with the crude NQ after recrystal, according to SEM images, the process of NQ product preparation using nitrate method by controlling crystallization is effective.