As a form of teacher collaboration, lesson study has recently received increasing attention in teacher education. Existing research highlighted the importance of two types of collaboration: one between experts and in-service teachers, and the other between preservice and in-service teachers in a blended lesson study. However, limited research has been conducted on the tripartite collaboration among experts, in-service teachers, and preservice teachers. Nowadays, collaborative talk is often used to explore the collaborative mechanisms within teacher collaboration. In this vein, Pedagogically Productive Talk (PPT) has been employed as a theoretical framework to capture its patterns. This study explored the characteristics of collaborative talk among expert, in-service, and preservice teachers in a blended lesson study through the lens of the PPT framework, employing Epistemic Network Analysis (ENA) as the method of data analysis. This study particularly focused on two scenarios involving different types of experts: one being an academic expert and the other being a teaching expert with extensive teaching experience. Quantitative analysis reveals different patterns of collaborative talk between the two groups, and this study also provided insight that the inclusion of the preservice teacher contributes to the effective conduct of the collaboration mentioned above.