To improve the crystal morphology of 2, 6-diamino-3, 5-dinitropyrazine-1-oxide(LLM-105) and control the crystal size distribution of LLM-105, the metastable zone width of LLM-105 in dimethyl sulfoxide(DMSO) was measured by turbidity method using a CrystalSCAN multi channel crystallization instrument. The effects of initial concentration, stirring speed and cooling rate on the metastable zone width were studied. The nucleation orders effected by cooling rate were calculated based on the classical nucleation theory. Results show that in the cooling crystallization process, the metastable zone width of LLM-105 in DMSO narrows with increasing the initial concentration and stirring speed. The metastable zone width broadens with increasing the cooling rate. The optimal crystallization conditions obtained are initial concentration of 0.0700 g·mL^-1, stir speed of 390 r·min^-1 cooling rate of 1.0 ℃·min^-1. The nucleation order increases from 1.825 to 2.5747 when the initial concentration increases from 0.0670 g·mL^-1 to 0.0750 g·mL^-1. Under the optimal crysallization conditions, the controllable high quality LLM-105 columnar particles with smooth surface, ruly morphology and particle size of 60 μm are obtained by adding the 2.5 g LLM-105 crystal seed with particle size of 4 μm into DMSO-LLM-105 solution.