It becomes popular that teachers use museum resource to assist teaching, however, the key of success relies on whether teachers would change their habitual teaching perspectives in order to adjust non-formal educational environments of museums. Therefore, this study explores teachers’ learning experience of utilizing science museums, focusing on how teachers change their customary assumptions into more inclusive, discriminating and integrative perspectives on the use of museum resources. The study adopted Mezirow’s transformative learning theory as the theoretical framework, and used qualitative, in-depth interviews with three “Honor Teacher” awarded by National Museum of Natural Science. The findings showed that the natures of teachers’ transformative learning experience are varied, however, they all include three key elements, such as gestation and catalysis, reflection and exploration, integration and action. This study also found that teachers’ transformative learning experiences are influenced by contextual factors, namely teacher personal, museums and schools. Finally, suggestions were made regarding how to help teachers to transform their teaching beliefs in order to use museum resources more successfully and effectively.