本論文是從群論中的【西羅定理】的應用,再搭配上【半直積】的作用下,所描述出群的構造;所以本人就從【西羅定理】與【半直積】相關的主題下手,但考量自身的能力與時間,故只能針對群論中元素個數為pq^2的這種特殊群來整理與分類。 In this paper,we study the groups of order pq^2 with p and q distinct primes. Through the method of semidirect product,we shall be able to characterize the structure of such groups.