Visualization study on the interaction of the Taylor flow behavior and the catalytic activity in a gasliquid-solid microreactor for nitrobenzene hydrogenation was performed under the long-term operation. The results showed that the gas slug length was first declined rapidly due to hydrogen consumption and then almost unchanged along the flow direction. After operating with a few hours, the variation of the gas slug length became obscure at the upstream due to the nanocatalyst deactivation but obvious at the downstream. Finally, the gas slug length was nearly unchanged. Corresponding to the long-term operation, the nitrobenzene conversion was first kept stable and then gradually declined, which well responded to the flow behaviors. Besides, effects of the inlet nitrobenzene concentration and flow rates on the flow behaviors were also explored. This work reveals the inherent interaction between the Taylor flow behavior and catalytic reaction under the long-term operation. (C) 2017 Elsevier Ltd. All rights reserved.