Understanding and supporting pre-service teachers' creativity in collaborative instructional design has gained increasing attention. To design novel and effective learning experiences or activities for students, they need to build empathy with students, that is, understanding students' learning needs. This study aimed to (1) explore the patterns of design cognition in empathy-scaffolded pre-service teachers' collaborative instructional design, and (2) investigate the differences in patterns of design cognition caused by two empathy interventions. Two classes, comprising 64 pre-service teachers, were randomly assigned to either the experimental condition (that used structured empathy strategy) or the control condition (that used unstructured empathy strategy). The pre-service teachers worked in groups of 3-4 members to perform design tasks. Their group discourses were audio-recorded and coded; an epistemic network analysis (ENA) was used to analyze the coded data to reveal the design cognitive processes and patterns. The ENA results revealed that empathy was cyclical and intertwined with defining problem and ideation (including generating ideas, building on ideas, elaborating and selecting ideas). Group discussions concentrated more on ideation than empathy. The comparison between the two interventions showed significant difference in design cognition. The experimental groups' discourses exhibited stronger co-occurrences between empathy and ideation, between defining the problem and generating new ideas, and between building on ideas and elaborating ideas. In contrast, the control groups' discourses were less focused on empathy, they concentrated more on the ideation processes. Regarding product creativity, there was no differences in terms of usefulness and novelty across the two conditions. This study can deepen understanding of the complexity and dynamic nature of pre-service teachers' collaborative instructional design.