In solving mathematics problems, pre-service mathematics teachers differ in their communication styles. However, no recent research has focused on classifying pre-service mathematics teachers’ mathematical communication styles for solving non-routine problems, particularly those in three-dimensional geometry. The present research is a descriptive qualitative which aim to analyze pre-service mathematics teachers’ mathematical communication skills and classifying them into three categories. The subjects consisted of pre-service mathematics teachers willing to be volunteers, employed mathematical communication in problem solving, and could implement think-aloud approaches in their mathematical problem solving. Data collection methods include non-routine tests, observations, and in-depth interviews. Data validation techniques included source triangulation. The results showed that the pre-service mathematics teachers engaged in three categories of mathematical communication: notation, visual, and argumentation. Pre-service mathematics teachers in the notation category tended to represent mathematical problems in the form of notations, such as mathematics symbols. In the second visual category, the students visualised the information into a picture or a diagram. The third category was argumentation, which consisted of pre-service mathematics teachers who tended to answer questions by presenting logical and systematic arguments.