In this study, tree ring samples of Sabina przewalskii were collected from 12 sites in the different geographical areas on the Qinghai Plateau. These were used to develop 12 tree ring width chronologies using standard dendrochronological methods. The characteristics of the temperature field and tree ring width field were analyzed,and the MayJune maximum temperatures in past 300 years were reconstructed using 12 tree ring chronologies and meteorological data from 30 stations on the Qinghai Plateau. The analysis shows that the first eigenvector that is typical of the Qinghai temperature field and tree ring width has a field correlation coefficient of -0.465 (P < 0.01). The first characteristic change of the two fields is synchronization. The high value center of the first eigenvector is located at Qilian Mountains and Qaidam Basin on northern Qinghai, and the low center is located at southwest and southeast (Animaqing Mountains) on Qinghai Plateau. The May-June maximum temperature field in past 300 years had five warmer stages, five colder stages, and five continuous warming and four continuous cooling stages, with slow warming and rapid cooling. The coldest period was in the 1830s1840s, the longest colder period was from late 19th century to early 20th century, the warmest period was in the 1930s-1950s, and the longest warm period was from late 18th to early 19th century. Since the 1960s, the temperature of May-June has risen continuously on the Qinghai Plateau, and it has risen particularly sharply from the 1980s to the present. We detected significant changes (P< 0.05) in the May-June maximum temperature field in past 300 years, with 2.1, 3.1, 8.5, 25.5-yr and 68.0year quasi-periodic changes. The MayJune average maximum temperature was influenced by the southwest monsoon and westerly winds on the Qinghai Plateau. This work presents representative reconstructed temperatures for most of the Tibetan Plateau, even in the southwest monsoon region.