The Irtysh River basin is a significant part of North Xinjiang, where snow and ice meltwater, as well as precipitation,are abundant. The total water resources, which mostly make up of snowmelt runoff, come second in Xinjiang, with the main flood season from spring to early summer. Hydrological processes respond obviously to climate warming and increasing precipitation. In order to ascertain the variation and to predict possible climate change in the study area. Air temperature and precipitation's mean and extreme values in the last 50 years are analyzed with Detrended Fluctuation Analysis. It is found that annual, spring and summer precipitations have long-range correlations, and will maintain this trend for a long time. Autumn and winter precipitations are less sustainability with strong randomness. Annual mean, summer, autumn and winter temperatures also have increasing tendency. However, spring temperature may have long time scale variation. In a nutshell, air temperature continually rising has relatively higher possibility than precipitation rising. But the dominant factors are different. Regional precipitation change is more likely associated with the anomaly of atmospheric circulation. Extreme thresholds calculated by DFA and corresponding figures indicate that since the 1980s, extreme high temperature and extreme precipitation events has begun to increase whereas extremely high values have not improved significantly; extreme low temperature events have reduced sharply and values have increased distinctly. Compared with other climate factors, winter temperature shows higher sensitivity to climate change.