To reveal the thinking asymmetry of yin and yang transformation and its cognitive neural mechanism using event related potential(ERP) and functional magnetic resonance imaging(fMRI).Methods:ERP and fMRI were used to record the response time，accuracy rate，EEG signal and blood-oxygen-level-dependent(BOLD) signal of 30 postgraduates of traditional Chinese medicine(TCM) in judging yin and yang transformation，and statistical analysis was performed.Results:The response speed of TCM postgraduates in judging yang to yin transformation was faster than that in judging yin to yang transformation.ERP results indicated that the asymmetry in later stage of cognitive processing of yin and yang transformation was related to the advantages in attention resource allocation of yin to yang transformation，working memory process，semantic analysis and situational integration.In fMRI experiment，the right insula and right middle frontal gyrus had asymmetric cognitive responses to yin to yang transformation，suggesting that emotional processing and reward mechanism might be closely related to maintaining the working memory of yin to yang transformation，while the middle frontal gyrus might participate in the inhibition of negative information to promote the semantic integration of yin to yang transformation.Conclusion:There is asymmetry in the cognitive processing of yin and yang transformation，and the right hemisphere of the brain has different cognitive processing modes of yin and yang transformation.