The purposes of this study were to explore students' learning styles and teachers' teaching styles and study the effects and interaction effects of learning styles and teaching styles on mathematics achievements. The subjects were 3,382 ninth-grade students and 110 mathematic teachers. The main results revealed that most students were categorized in the reflector style (26.11%), whereas most teachers were categorized in the facilitator style (34.55%). Also, the two groups of learning styles and the three groups of teaching styles had direct effects significantly, and they had 76.47% interaction effects in all matching between them (30.77% matching and 69.23% mismatching) on mathematic achievements. The theorist students were the most advantageous group whereas the reflector students were the most disadvantageous group of learning styles in learning mathematics.