The liquid flow rate affects the residence time between the substrate and the catalyst by changing the liquid holdup in the micro-packed bed reactor. A residence time that is too short will easily lead to an increase in the selectivity of the reaction intermediates, and a long residence time will also reduce the productivity of the system to a certain extent. As shown in Fig. , when we set the material through the reaction tube at a flow rate of 2.5 mL/min, most of the remained unreacted and kept in the reaction liquid, and the BN conversion rate was only 42.06%. When the flow rate was gradually reduced to give BN and the catalyst sufficient contact time, we observed that the conversion rate increased linearly until 0.5 mL/min when the substrate conversion was complete and the selectivity of the target product was ensured. We set the flow rate under this condition as the optimal contact time. The above experimental results show that under the optimized reaction conditions, the Co@CS catalyst can catalyze the hydrogenation of BN in a continuous flow mode in a micro-packed bed reactor, and the highest benzylamine yield can be obtained at 80°C, 0.5MPa, 0.5mL/min flow rate, and 7M ammonia methanol solution. To test the stability of the catalyst, we also conducted a long-term test on the reaction. The continuous flow process helps to evaluate the activity of the catalyst. We synthesized benzylamine for a long time in a reaction cycle of up to 30 h, and all conditions were set to the previously optimized values. We were surprised that the catalytic system performed robustly in the long-term test, and the target product was harvested with excellent yields throughout the process. Moreover, the catalyst maintained excellent reactivity and product selectivity without losing activity significantly. Compared with traditional tank reactors, continuous flow technology can greatly shorten the reaction time, making it possible to synthesize primary amines on a kilogram scale per day or a ton scale per year, which further makes flow hydrogenation convenient and feasible for industrial production.