The monobenzoylation of o-phenylenediamines (DA) is an important process to synthesis N‑(2‑aminophenyl) benzamide (MP), which is a key intermediate of many active compounds. But the monoacylation is difficult to control because this process is a kind of consecutive reaction system and the two amine groups located in a similar chemical environment. To understand the effects of reaction parameters on the selectivity and further optimize operating conditions, a microreactor platform was developed to evaluate the kinetics of the acylation reaction of DA and benzoic anhydride (BH). A kinetic model was established, and the reaction order of each reactant, the values of kinetic constants, pre-exponential factors and activation energies were determined. Validation experiments showed the model is in good agreement with the experimental results. The model simulation indicated that high reaction temperature and molar ratio of DA and BH is necessary to improve reaction efficiency and selectivity.