Abstract Revealing interdisciplinary patterns is a cornerstone for the continued evolution of research, education, and societal progress, providing a scaffold upon which to build a more collaborative and integrated approach to knowledge creation. This study presents a novel approach to identifying and analyzing the critical year for interdisciplinary citations (CYIC), which was defined as the year in which qualitative change in interdisciplinary knowledge flow occurred. We conducted two experiments using a Chinese paper dataset spanning 106 disciplines from 1992 to 2022, with the first to pinpoint the occurrence of CYICs and the second to examine three patterns of interdisciplinarity following these CYICs. Our findings revealed that 85% of disciplines exhibit CYICs, often corresponding with a transition from unidirectional output to reciprocal knowledge cooperation. Furthermore, we found that datasets after CYICs are generally characterized by increased interdisciplinarity of knowledge, albeit without a corresponding rise in the interdisciplinarity of disciplines or interdisciplinary diversity. Our results suggest that policy shifts and societal needs are pivotal in driving the formation of interdisciplinary collaborations, as exemplified by the surge in mutual interdisciplinary citations in response to China's poverty alleviation efforts and western development policies.