20 1 1 year. The 2023 high school graduates entered primary school in September, 20 1 1. The educational system of primary schools, junior high schools and senior high schools in China is six years for primary schools, three years for junior high schools and three years for senior high schools. That is, it takes 12 years from primary school to high school graduation. The class of 2023 high school graduates started primary school in September 2023-12=20 1 1.