At present， global scientific and technological competition is becoming increasingly fierce， and key core technologies have become the focus of the game of great powers. The experiences of catching up in major national equipment provide new insights for China’s modernization and high-quality development. Existing studies have focused on a unidirectional catching-up perspective with reference to the leader， without fully exploring the dynamic competitive interaction process between the leader and the catching-up. Based on the “action-response” framework of dynamic competition theory， it selected the shield machine technology catching-up process of China Railway Construction Heavy Industry Corporation Limited （CRCHI） as the research object to investigate the dynamic competitive interaction mechanisms in China’s shield technology catching-up process. The results reveal that during the technological catching-up process， the competitive strategic actions between the leader and the catching-up exhibit complex interactions， characterized by a complex iterative interaction pattern of “hostile defense of the leader-stealthy offense of the catching-up-aggressive action of the leader-proactive precautionary of the catching-up”. Leader and catching-up character attributes reverse with the stage of competition. In the catch-up stage， the leader values defense and the catching-up values attack； in the overtaking stage， the leader values attack and the catching-up values defense. Different from some of the first breakthroughs in basic technology， and then the pursuit of higher-level technological breakthroughs in the order of logic， the shield machine field follows a kind of reverse logic from the overall system to the local technology anchor point. It not only enriches the research on catching-up in major national equipment technologies， but also provides theoretical and practical guidance for the catching-up practices of latecomer firms.