The purpose of this study is to contribute insights into how math creation integrated peer tutoring can facilitate students' mathematical expression and explanation. Twenty-five second-grade primary students play the role of teachers to construct their math creations as the teaching materials to teach their partners. Specifically, the students need to solve given word problems and produce three forms of creation-including drawing expression, arithmetic expression, and solution explanation-to justify their solutions. This study shows that peer tutoring can promote students' drawing expression and solution explanation by providing opportunities for students to reexamine their math creation mutually. However, the progress of arithmetic expression does not achieve significantly. Besides, this study also finds that high and low achievers have different sequences in completing math creations and ways of participation. Finally, how computers facilitate and change students' mathematical expression and explanation compared with paper-based environment is also discussed.