The collection of fossil wood growth rings data is helpful for rebuilding paleoclimate.Based on the statistical analysis of fossil wood growth rings from Middle Permian Taerlang Formation in the northeast edge of Tuha basin,the paleoclimate evolution of Middle Permian is reconstructed for the first time.The analysis of fossil wood growth rings shows that this area was subject to north subtropical climate with obvious seasonal variations during the Middle Permian.The paleoclimate was relatively warm,but intermittent hot climate had occurred.The low percentage of latewood and the abrupt transition between earlywood and latewood of some growth rings reflect that the seasonal variations were very obvious during the period of trees'growth.The paleoclimate was prevailed by a subtropical monsoon climate with hot and humid summer and dry and cold winter.The relatively high mean sensitivity(MSaverage of 0.4)of fossil woods indicates that trees were influenced by monsoon climate during the growth period,and the environment was very unstable with uneven annual precipitation.The change of consecutive growth ring width and the existence of false rings implies that the climate changed frequently and generally was humid with arid and semi-arid fluctuations.