Abstract: Using daily temperature data at 642 stations in China Mainland from 1961 to 2000, the decadal variation and change in temperature-defined growing season over the past 40 years were analyzed. The growing season increased 6.6 days in China as a whole, 10.2 days in the northern China, and 4.2 days in the southern China. The largest increase in growing season, 18.2 days for the period, occurred in the Qinghai-Xizang Plateau. The most rapid increasing of growing season was in the 1990s, and 1998 is likely to be a year with the longest growing season in past 40 years.