The study investigated the nitration of 2-methyl-4，6-pyrimidinone （MPO） with nitrate sulfur mixed acid in a microchannel reactor， and further prepared 1，1-diamino-2，2-dinitroethylene （FOX-7） through hydrolysis reaction. N-octane was introduced as an inert solvent to generate slug flow for the reaction system. The reaction occurred inside disperse droplets， thus solving the problem of clogging of nitration intermediates in the microchannel reactor and achieving process intensification and continuous operation. The effects of reaction temperature， residence time， material ratio， and hydrolysis conditions on the product yield were investigated. The combination of microreactor and stirred reactor was proposed. At the molar ratio of nitric acid to MPO of 4.4， reaction temperature of 30 ℃， and residence time of 3 min in the microreactor followed by a 30 min insulation reaction in a stirred kettle， and the ring-opening realized by the hydrolysis with ice water for 2 h， the yield of FOX-7 could reach 90.1%， with a purity of over 99%.