The clustering analysismethod is used to divide the temperature field in sp ring and summer over the Qinghai - Xizang Plateau into three areas for p redicting the temperature trends of different areas. Based on the correlation between the temperature indexes in sp ring and summer over the Plateau and the Pacific SST in the p receding season, the SST distribution index is defined. When the winter SST over the western Pacific is higher ( lower) than normal, the sp ring temperature in Areas II of the Plateau is higher ( lower) ; while the winter SST in the western and eastern Pacific is higher ( lower) than normal, the summer temperature over southern Areas II and Areas III of the Plateau is higher ( lower) . Further analysis are conducted about the correlation between these two SST distributions and the 500 hPa geopotential height field in sp ring and summer in the Northern Hemisphere. The results show thatwhen the winterwestern Pacific SST index is higher ( lower) , the cold air activities over high latitude weaken ( strengthen) and itsmoving route northward ( southward) ; meanwhile, the geopotential height field is lower ( higher) , it is advantageous ( disadvantageous) to the southern air currentmoving northward and the circulation conversion from the winter type to the summer one, and the sp ring temperature over the central Plateau is higher ( lower) than normal. In contrast, when the integrated index ofwinter SST in the western and eastern Pacific is higher ( lower) , the northern Plateau to southern central - Siberia ridge and the western Pacific subtrop ical high in summer strengthen (weaken) , and the Plateau controlled by high system, the summer temperature over the central and southern Plateau is higher ( lower) .

Based on the 250一year annual mean temperature sequence reconstructed by multi—piece of tree—tings in the Qinghai Plat-eau．the abrupt change characteristics and inter—annual variation of annual mean temperature there are synthetically analyzed by using methods of linear tendency，wavelet analysis and abrupt change test．The result shows that annual mean temperature fluctuated remark—ably in recent 250 years in the Qinghai Plateau，and the 30一year moving—mean presented higher annual mean temperature during 1779—1811 and 1934—2006，and the highest annual mean temperature(1．3 )in 1998；while lower annual mean temperature dur-ing 1740—1778 and 1812—1933，and the lowest value(一1．5 )occurred in 1823，but annual mean temperature generally kept ris—ing．On relatively large scale beyond 20一year ，the seven alternations of coldness and warmness for annual mean temperature appeared obviously．On time scales of two to three years，28一year，48一year an d 110一year，the cycle variation was comparatively evident．

Using those data such as daily mean temperature, monthly precipitation and daily minimum temperature of 6 representative
weatherstations in Chaidamu basin, we analysed the characteristic of climate change and its influence on agricultural production
during recent 40 years .To make full use of changed agricultural climate resource and reduce the invalid influence, some suggestions
were proposed.