本研究旨在探究臺灣高級中等學校少子女化的趨勢，以政府的資料庫為分析範圍，採趨勢分析和集群分析等方法，獲得下列研究結論：一、公私立學校招生比率之差距將加大：公立學校大都屬於招生穩定型學校；私立學校有64校屬於招生不穩定型學校，56校屬於面臨退場型學校，故在少子女化的招生競爭下，未來五年公立學校之招生比率，將更大於私立學校，尤其公立高職有加大招生比率之空間。二、各校招生競爭更為激烈：臺灣本島各就學區於2017至2021學年度高一入學人數明顯下降，所以未有辦學特色之學校（招生率佳，招生率呈現隱定），即招生率不佳之學校，必面臨招生壓力。三、預測招生率不佳之學校招生更為艱困：2017至2021學年度預測招生率低於58%者，面臨極為嚴峻之招生考驗，即面臨退場型學校及招生不穩定型學校之招生將更為艱困；而預測招生率低於22%之私立學校將面臨退場。

This study aimed to explore the trend of fewer children and its effects on senior high school enrollments. Trend analysis and cluster analysis were used, and the data were drawn from the database of the Taiwan government. Main findings of the study include: 1. The gap between public senior high enrollments and private senior high school enrollments will widen. Public senior high school enrollments will remain stable; 64 of the private senior high schools will suffer unstable enrollments, and 56 of them will face withdrawal. In the coming five years, students who attend public senior high schools, especially public vocational high schools, will outnumber those that attend private senior high schools. 2. Student recruitment will get more competitive among schools. On the island of Taiwan, during the academic years between 2017 and 2021, the enrollments of first-year senior high students in all school districts will fall dramatically. Schools will face more pressures of student recruitment except for those that have their unique characteristics (i.e. those that have good and stable student enrollments). 3. It is predicted that problems with student recruitment will become more serious for the schools that have low student enrollment rates. In the academic years 2017-2021, schools that have a student enrollment rate of 58% or lower will be faced with withdrawal or unstable enrollments. It is further predicted that a student enrollment rate of 22% or lower will force a private school to withdraw.