Based on the daily mean temperature data of Yuping National Terrestrial Weather Observatory from 1961-2016, the starting date and the length of four seasons in Yuping County were statistically analyzed by using the Chinese meteorological industry standard QX/T15-2012. The results show that:(1) Yuping county year of the four seasons starting date: spring March 5, summer May 23, autumn September 22, winter November 28; Seasonal length: spring 79d, summer 122d, autumn 67d, winter 97d. (2) In the past 56 years, the spring start date of Yuping has shown an earlier trend and the length has increased, both of which took turns around the 1990s, but did not produce a climatic mutation; The trend of summer beginning date and length was not obvious. The beginning date of autumn was pushed back, and the length change was not obvious. The beginning date of winter did not change significantly and the length decreased. The increase of spring length and decrease of winter length are mainly due to the early start of spring. (3) The starting date of four seasons in Yuping County varies greatly from year to year