By using the monthly temperature,precipitation and greenhouse gases data from 88 meteorological stations in the Qinghai-Tibet Plateau from 1961 to 2012 as well as climate change scenarios data determined by CMIP5,several truth about warm and wet climate in the plateau for the 52 years are analyzed. The correlations among greenhouse gas,plateau heating field,plateau monsoon and the Arctic Oscillation (AO) index with its inter-annual oscillation are revealed. The possible climate change trend in the future 30-50 years is predicted. The results show that the warming trend has been alleviated since 2006 with a totally warming for 52 a; compared with global change,it has delayed for 8 a; precipitation has increased obviously in the plateau; climate wetting has delayed as compared with warming; 5 a short period precipitation variation has been not significant,instead of 12 a and 25 a period precipitation variation. With the greenhouse gas and aerosol increasing,plateau summer monsoon has enhanced,ENSO events and solar radiation has decreased,climate in the plateau has become warmer continuously but eased; plateau heating field has enhanced in spring and plateau summer monsoon has erupted early and kept strong,which lead to more rainfall in spring and summer,as well as the annual precipitation; yet in autumn and winter,AO has been relatively stable,east Asian trough intensity also has changed not obviously,as well as the plateau winter monsoon,as a result,precipitation in autumn and winter also has changed insignificantly. Temperature and precipitation in the plateau will be kept increasing in the future 20-40 years.