To prepare nitroguanidine of high bulk density,a technology converting needle-shaped to spheroidal nitroguanidine was studied through adding crystalline growth retardants based on orthogonal experiments. Methyl cellulose and polyvinyl alcohol were used as the retardants. Stirring rate,cooling speed and concentrations of two retardants were considered as experimental factors in orthogonal design for aqueous solution of nitroguanidine. Bulk density of the spheroidal nitroguanidine reached 1.12 g·cm^-3 under conditions of 1.5 wt% methyl cellulose,1.5 wt% polyvinyl alcohol,cooling rate of 0.4 ℃·min^-1 and stirring speed of 800 rpm.