Loess Plateau is the central region of Mainland China and its fragile ecological environment and frequent extreme climate greatly impact human production and life. Based on the 138 meteorological site observation data, using the method of monadic linear equation and Mann- Kendall for 27 of the Loess Plateau region’s spatial and temporal variations of extreme climate index not only help promote the Loess Plateau area’s ecological environment protection and soil and water conservation management, but also strongly provide a decision support for regional sustainable development in the Loess Plateau. By studying the trends of extreme climate index and mutation, the following conclusions are generated: (1) The Loess plateau of extreme temperature index of frost days (FD0), ice days (ID0), monthly maximum value of daily minimum temperature (TNx), and cold spell duration indicator (CSDI） are decreasing gradually; Growing season length (GSL), summer days (SU25), tropical nights (TR20), monthly maximum value of daily maximum temperature (TXx), and warm spell duration indicator (WSDI) are increasing continuously, while the rest of the index change vary more gently. In general, the cold index and the warm index of the Loess Plateau’s extreme temperature index are decreasing gradually. (2) There are spatial differences in the extreme temperature indexes. In addition to the indexes consistent with the changes of the whole region, cool days (TX10P), cool nights (TN10P), monthly minimum value of daily maximum temp (TXn), monthly maximum value of daily maximum temp (TXx), and diurnal temperature range (DTR) are different in sub-regions and the whole region, which are mainly manifested in the Loess tableland, hilly Loess, and rocky mountain areas. (3) The variation trend of extreme precipitation index is flat and close to the multi- year average. Simple daily intensity index (SDII) and very wet days (R95p) showed an upward trend, while consecutive dry days (CDD), extremely wet days (R99p) and consecutive wet days (CWD) showed a downward trend. However, the change trend was not obvious on the whole. In terms of spatial distribution, except for wet days (R99p), very wet days (R95p), simple daily intensity index (SDII), strong precipitation, and annual average daily precipitation intensity are consistent with the variation trend of the whole region in each sub-region. Other indexes are different from the variation trend of the whole region in each sub- region and are mainly manifested in Loess tableland and girder hills. (4) Most of the abrupt transitions of extreme temperature indexes occurred in 1980—1985 and 2010—2015, while most of the abrupt changes in the extreme precipitation index occurred from 1985 to 1990 and from 2010 to 2015. Comparing the abrupt transition nodes of the two, the abrupt transition time node of the extreme temperature index is relatively earlier than that of the extreme precipitation index.
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