<p>No one doubts that mutual mistrust is responsible for the unprecedented dangerous deadlock between China and Japan. There is a wealth of research on Sino–Japanese mutual mistrust. However, the conventional wisdom typically focuses on unique Sino–Japanese relations in shaping mutual mistrust. Over-emphasizing the uniqueness of Sino–Japanese relations has produced an "unproductive intellectual confrontation". In reality, both China and Japan have demonstrated their intentions and efforts for building mutual trust, but the mutual mistrust has deepened. Why has this seemingly abnormal situation happened? The representative case is the failure of the 3.11 disaster diplomacy between China and Japan. Why was such an unprecedented opportunity lost despite the initial relatively high expectations from the both sides? Furthermore, why did disaster diplomacy not contribute much in improving bilateral trust, but rather seems to have enhanced the mistrust between China and Japan? The existing literature seems to be largely insufficient to provide convincing explanations. It is necessary to reconstruct and re-theorize the research on Sino-Japanese mistrust.</p><p>To these ends, this paper introduces, first, the theories of misperception and mistrust in international relations. Then it uses the failure of Sino–Japanese disaster diplomacy around the 3.11 Great East Japan Earthquake as a case study, showing that even the initial gestures of goodwill could be distorted by entrenched biases to produce even more mistrust. Due to the negative mutual perceptions that began to solidify in 2010, even incoming goodwill messages from the other side have been unconsciously filtered or processed to fit with solidifying misperceptions. The fundamental problem originates in the different over-expectations of China and Japan from disaster diplomacy. The lack of timely and efficient communication enhanced the misinterpretation of the other side's intentions, which was followed by frustration and suspicion. When the public and the media have raised frustration and suspicion, political elites have generally lost domestic space to counter mistrust or tensions between states.</p><p>The paper shows that misperception and mistrust can be replicated unconsciously and unnecessarily in many scenarios. There is both theoretical and policy relevance in this project. The project tries to integrate Sino–Japanese relations research with more general international relations studies. In so doing, it would be helpful to provide an alternative intellectual explanation of Sino–Japanese relations with a more universally acceptable understanding. In terms of policy implications, the project will provide insights as to how the process of the formation of misperception and the replication of mistrust between China and Japan have evolved. Lessons can be drawn from this research in order to avoid or minimize unnecessary misperception in the future.</p>