Abstract: Diagnostic studies en the climate change and variability were reviewed. The main subjects were the global mean temperature and precipitation, temperature and precipitation in China. ENSO and QBO. It was indicated that global mean temperature experienced a warming during the 20th century. The 1980's was the warmest decade since the instrumental observations became available. However, the temperature change in China differed from the global one. The warmest decade in China was the 1920's and 1940's. Mean temperature of the 1980's was near normal. Global mean precipitation showed also an increasing trend. But, the greater positive anomaly was found in 1950's and 1970's. Mean precipitation anomaly of 1980's was near normal. The main climatic characteristics of China was cold/wet or warm/dry during the last one hundred years or so. The decade of 1920's and 1940's was the driest in China for this period. The ENSO events were identified according to SST and SOI from 1871 to 1993. 28 El Nino and 21 La Nina events were found. The frequency of El Nino increased some what when the global temperature was higher than the normal. and that of La Nina inc;eased in the cold periods. The mean length of QBO of the equatorial zonal wind in the stratosphere from 1951 to 1993 was 28.7 months. The QBO phases were reconstructed for the period of 1873-1950 according to the numbers of subtropical cyclone in North Atlantic and Indian monsoon rainfall. No evidence was found to show any significant relationship between the QBO and the global climate change.