Since 2001, in accordance with the requirements of the statistical system, the base period of China's CPI was rotated every five years. Beginning in January 2016, 2015 was used as a base period in the new round of rotation, and the base periods in the previous three rounds were 2000, 2005 and 2010. Compared with the base period in the last round, the survey directory and specifications of the new base period were closer to international standards, and a number of new products and services were included, which could further reflect changes in consumption and economic structure. At the same time, the weight numbers of CPI composition were adjusted accordingly, according to the latest results of the survey on residents income and expenditure. The survey directory of the new base period was revised following the Classification of Individual Consumption According to Purpose (COICOP) developed by the United Nations and the Classification of Household Consumption Expenditure (2013) enacted by the NBS. According to estimation, the current rotation of the base period had almost no influence on the month-on-month data of CPI, and a little influence on the year-on-year data, which was about 0.08 percentage points.