After the “Double Reduction” initiative was officially kicked off，the central government requires us to do two subtractions—effectively alleviate the students’ burden of homework and off-campus training，and also two additions—fulfill the task of “double improvement”，i.e.，to improve the quality of class teaching and the level of after-school services. Based on literature research，by sorting out and analyzing the historical context of primary and secondary schools’ after-school services in some developed countries as well as the main characteristics and trend of after-school service policies，this Report proposes to construct an after-school service system with the collaboration from multiple departments，build a professional team of after-school service practitioners，and strictly implement the procedures and standards of quality supervision and evaluation，so as to provide references for improving the level of after-school services in primary and secondary schools in China.