This work indicates that the nitration of guanidine salt can be carried out in continuous mode using the microreactor system. With sulfuric acid guanidine as raw material and sulfuric acid and sulfuric acid mixture as nitrating agent，the influences of the mixed acid concentration, reaction temperature, residence time, ratio of two materials on the yield of nitroguanidine were carried out. The optimal reaction conditions are shown as follows: 90% HNO3: 98% H2SO4 = 2: 1 (v / v), 1:1. 2 of molar ratio of sulfuric acid guanidine and nitrating agent. The conversion of the sulfuric acid guanidine can reach 87.9% and the yield of the nitroguanidine can reach 86.1%. Compared with the traditional process, new technology based on micro-channel continuous flow greatly improves production efficiency and reduces costs.