Centered on the Tibetan Plateau (TP),the Third Pole region contains the highest concentration of glaciers outside of Polar Regions. Ice cores in the TP can provide important information for the paleoclimate and paleoenvironmental research. However, interpretations on the water stable isotope records in Tibetan ice cores, especially in the southern TP where is seasonally influenced by the Indian monsoon,are still somewhat controversial. In this research, therefore, delta~(18)O records of 10 ice cores (Muztagata, Dunde, Malan, Puruogangri, Geladandong, Longxiazailongba,Noijin Kangsang, East Rongbuk-1998, East Rongbuk-2002, and Dasuopu) equally distributed over the northern TP and the southern TP are integrated, respectively, and the relationship between the two composite delta~(18)O records with the respective regional air temperature are discussed. The composite delta~(18)O record of the 10 ice cores is also compared with the instrumental air temperature on the whole TP. The individual Tibetan ice core delta~(18)O records and meteorological station air temperature records are first normalized by Z-score transformation and averaged on the respective geographic regions, and the correlations between the composite ice core delta~(18)O and air temperature are then analyzed during the period 1955~2004 A.D. The results show that the composite delta~(18)O time series over the northern,the southern and the whole TP are all significantly correlated with the respective regional air temperature records at the 99% confident level, with the correlation coefficients of 0.53,0.44 and 0.57. The correlations are improved when the 5-year running means are used. In addition, the correlations between the composite delta~(18)O record over southern TP and the summer monsoon rainfall series over North India, Northeast India and North Central India, and South Asian summer monsoon index are also analyzed. The weak and non-significant correlation coefficients of -0. 15, -0. 05, -0. 18 and -0. 08 suggest that the annual delta~(18)O record over southern TP is not directly controlled by the Indian monsoon related precipitation amount. The composite ice core delta~(18)O record over the TP is extended to 1900 A.D.,and the annual variation of air temperature during the twentieth century is thus constructed based on above statistical relationship. A good correlation (r=0. 59, p < 0. 0001) is observed between the constructed TP temperature and the northern hemisphere temperature. These analyses demonstrate that the water stable isotope records in the TP ice cores are definitely the proxy of air temperature,and that the spatially integrated stable isotope records are much better than the individual in exploring the past regional climate change.