Ideas mattered in China’s diplomatic decision-making during the Ming and Qing period. The Ming and Qing dealt with diplomatic affairs through the tributary system. The core of the tributary system was its asymmetrical and hierarchical relationship. China held the self-image of Tianchao, and the Chinese emperor claimed suzerainty over the whole world. Thus it had become the bottom line for the tributary system to maintain the trappings of Tianchao. The self-image of Tianchao limited the diplomatic choices for the Ming and Qing dyansties, the most important of which was that it ruled out the possibility of peace on an equal footing. In the cases of Ming’s peace talks and later Qing’s dealing with Western powers, China, even in the face of equally or more powerful forces, still refused to give up on the Tianchao illusion and rejected diplomatic equality. The Tianchao image hampered cool-headed strategy thinking or wise pragmatic decision-making and put China between a rock and a hard place. Consequently, the obsession with Tianchao status and tributary hierarchy had undermined the security and interests of China.