This study intends to suggest implications by comparing Korea's high school mathematics curriculum with the UK's high school mathematics curriculum ahead of the 2022 revision of the mathematics curriculum. The UK has revised assessments to emphasize post-16 mathematics since 2017. Accordingly, the contents of Key Stage 4, Core Maths and A-level, which correspond to the UK high school mathematics curriculum, were examined and compared with Korean high school math subjects. In the UK, mathematics education is emphasized at the high school level. In the UK national curriculum, students’ options for mathematics were expanded. In order to prepare for the future society, new mathematics subjects and evaluations were developed and implemented, and the A-level mathematics was improved. In addition, the subject-centered content was developed and continuously handled from Key Stage 3 to the high school stage, and it was structured to facilitate the internal and external connection of mathematics by linking it with the subjects of other areas. The implications of this UK high school math education for high school math education in Korea are: First, it is necessary to think about the content of learning to prepare for the future society. Second, support for math learning and development of subjects and evaluation at the same time. Third, it is necessary to improve the statistics curriculum to improve statistics education.