To reflect the country's economic growth, inflation and the implementation of monetary policies. Based on the monthly data of national debt yield from January 2015 to December 2019, these data are divided into 1 year to 30 years according to the maturity period, and the principal component analysis of the term structure of interest rate from 2012 to 2017 shows that the factors affecting the change of term structure of interest rate include level factor, skew factor and curve factor. The variance contribution rates of these factors to the variation of interest rate term structure curve are 82.2002%, 16.9948% and 0.6283% respectively. The horizontal factor represents the position of the term structure of interest rate, the skew factor represents the degree of skew of the term structure of interest rate, and the curve factor determines the interest rate.