The relationship between Kuroshio sea surface temperature index (KuSSTI) and the first frost dates (FFDs) in northern China are analyzed on the basis of observation data and reanalysis data. The results show that the monthly KuSSTIs of respective months of summer and early autumn have significant impacts on FFDs in northern China. The warmer (cooler) the Kuroshio SSTs are, the later (earlier) FFDs in North China, Huang Huai Region, northern Hetao Region, middle and northeastern Inner Mongolia and the region around the Bohai Sea are. Further analysis indicates that the warm (cold) Kuroshio SST anomalies significantly influence the general circulation from northern China, Japan Sea to north Pacific, increasing (decreasing) the 500 hPa geopotential height and weakening (strengthening) the East Asia trough. The lower level wind anomaly shows southeast (northwest) direction over North China and Huang Huai Region, weakening (strengthening) the cold wave from the north, so that the FFDs in North China and Huang Huai Region come later (earlier) than normal.