Tree-ring width data from south slope of the Heiertage Mountains, which is located to the south of Aheqi, Xinjiang, China, were collected to develop into chronologies. Correlation analysis between tree-ring width index and climatic factors of Aheqi meteorological station showed that tree radial growth was dominated by moisture status including precipitation, relative humidity and water vapor pressure. The optimum period and factors which is of high coefficient and physical significance, water vapor pressure from last August to current June in Aheqi was selected to establish the linear transfer function with tree-ring width standard index. The explained variance of the function is 66.4%. The observational data analysis in Aheqi indicated that precipitation, water vapor pressure and temperature show a consistent increasing tendency. Four drought periods (1666-1689, 1722-1749, 1820-1880, 1909-1988)and four wet periods (1688-1721, 1750-1819, 1881-1908, 1989-2002) were found in the reconstructed water vapor pressure series during 1656-2012. The drought and wet periods are also coincided with the reconstructed precipitation in Tianshan Mountains and Akesu, however, not with that from Baluntai in the central Tianshan Mountains in south Xinjiang. The multi-taper method (MTM) spectral analysis revealed the cycles of 56.8 a, 13.4 a, 10.7 a, 6.9 a, 5.4 a, 4.3 a, 3.8 a and 2.6 a above the 95% confidence level. In which, the cycles of 56.8 a at low frequency and 6.9 a at high frequency are correspondent with the reconstructed series in Tianshan Mountains. The abrupt increasing change in 1988 and the wet period since 1989 are consistent with the wetting trend in northwest China and especially in south Xinjiang.