The aim of this study is on the development of young children's arithmetic and geometric concepts. To achieve this aim, teachers motivated young children's curiosity through the use of interesting illustrated books. In particular, the target is the advance in young children's knowing and understanding of geometric figures and numbers within 10. There were altogether three phases. In the first phase, the investigator designed a mathematical activity (a pre-test) for the teacher to capture young children's entry behavior. The second phase referred to the use of illustrated books in ordinary instruction. During the third phase, the mathematical activity (identical to that of phase 1) was carried out again, in order to find out if advancement in young children's mathematical ability was present. Data collection and administration included investigator's observation notes; video analyses; notes on teacher interviews; and investigator's self reflections record. Data analyses and results were two: geometric concepts and arithmetic concepts. Geometric concepts. Using illustrated books could advance in understanding and increase in curiosity of young children; also to promote young children's recognition in variation in polygon; and arouse young children's imagination and creativity in individual figures and combination of patterns. Arithmetic concepts. Using illustrated books could cause the interests in change of numbers; cultivate young children's sensitivity in the addition and subtraction of numbers; and promote the ability of combination and decomposition of numbers within 10. The findings of this study suggested that illustrated books are important and useful in assisting young children to explore mathematical concepts. Illustrated books encourage young children to think and allow room for oral presentation, clarifying and reflecting one self. Finally, teachers are suggested to integrate the use illustrated books in teaching mathematics, and follow up with related mathematics activities, to upgrade young children's development in various mathematics concepts.