The purpose of this study was to design games by referring to multiplication and division units, then through a pilot test and modification and integrating modified games in mathematics teaching for elementary third graders, so as to investigate the performance and learning attitude of students and to analyze the advantages and disadvantages in the teaching processes. Results indicated that the children made progress in multiplication and division computation and behaved positively on learning attitude. Meanwhile, the cooperation and team spirit were enhanced and a closed and warm relationship between teachers and students was established. In the end, regarding the curriculum and activities design, the researcher made some recommendations. They are: integration of life experience of children, blend into various characteristics of games, good control of classroom order and time. The above results yielded instructional implications for teachers who consider integrating games into mathematics instruction for elementary school children in future.