This study examined the effects of shared representational guidance (collaborative textural representative tool vs. collaborative graphical representative tool; TR vs. GR) and prior knowledge (low vs. high; LPK vs. HPK) on different levels of individuals' understanding of specific-domain knowledge after collaborative problem solving (CPS). A total of 84 individuals who majored in education from the same university in East China participated in the study. Their pre- and post-test factual and conceptual knowledge understanding were measured and analysed. It was found that prior knowledge affected individuals' development of factual knowledge understanding after CPS. Individuals with high prior knowledge could obtain better factual knowledge understanding than those with low prior knowledge. Shared representational guidance impacted on individuals' development of conceptual knowledge understanding after CPS. Individuals in a group who used a collaborative graphical representative tool achieved better conceptual knowledge understanding after CPS than the one who used a collaborative textual representative tool. The findings in this study can provide teachers with some detailed instructional guides to organize CPS project in the classroom context.