Collaborative problem-solving (CPS) learning is increasingly valued for its role in promoting higher-order thinking of learners. Despite the widespread application of role scripts in CPS, little is known about the mechanisms by which roles influence learners' cognition and the impact of goal orientation on roles. In this study, we designed role scripts and goal-orientation scripts to facilitate CPS. Then, a total of 32 postgraduate students participated in CPS and they were divided into 8 groups, among which two roles of analyst and commenter were assigned respectively. Through qualitative and quantitative analysis, this study explored the differences between the two roles in terms of discourse space rotation, types of cognitive activities and epistemic network structure, and the function played by goal orientation. Results showed that there was a general structure in CPS, that analysts and commenters have different functional biases, and that goal orientation influences the function of the roles. This study clarified the cognitive contribution of different roles, and the respective strength of different goal orientation. The findings may provide instructors with implications for designing scripts and organizing CPS in the classroom context.