The concept of joint operation, which have been uphold the US armed forces in recent years, have important implications for the reform of Taiwan's war-fighting command system. In the face of China's military threat, Taiwan's defense will be characterized with little warning and short-time lasting; therefore, it is needed for Taiwan to develop a sound command system for joint operation, so as to facilitate rapid reaction capabilities and integrate war-fighting effectiveness among services. From the perspective of US model, several key points should be enlisted on the top of Taiwan's reform agenda on the command system for joint operation. They have included: clear command relationships, brief command chains, rapid reaction capabilities, unified command and force integration. To Taiwan, it would be a crucial measure to develop new organizational concepts, implement the transformation of command system, and improve joint war-fighting effectiveness, in order to cope with the military threat from China in a future war.