One year. According to official website, Education Bureau of Xi, Xi 'an school district is divided once a year in accordance with the general goal of "enrolling students by their source and entering the school nearby", and the division of school districts is relatively stable and moderately adjusted, focusing on single school division and exploring the principle of multi-school division. Xi 'an, referred to as "Gao", was called Chang 'an and Haojing in ancient times. It is the capital of Shaanxi Province, a sub-provincial city, a megacity, the core city of Guanzhong Plain urban agglomeration, and an important central city in western China determined by the State Council.