Based on the theory and method of dendrochronology, we studied the response relationship between the radial growth of Populus euphratica and the temperature and runoff in the middle reaches of Tarim River by means of interdecadal mean, correlation analysis and multiple linear regression, in order to understand the radial growth law of P. euphratica and its response to environmental change, and finally to provide a theoretical basis for the protection and management of P. euphratica forest. The results show that: (1) during the period from 1983 to 2014, the periods with the highest temperature and the lowest runoff in the middle reaches of the Tarim River occurred between 2005 and 2009, and the annual ring width of P. euphratica reached the minimum during this period; From 2010 to 2014, the width of the annual rings of P. euphratica appeared to be the largest and narrower. (2) The radial growth of P. euphratica in the section of Shazihekou is mainly affected by the runoff in the growing season from April to September. The runoff in the previous year also has a certain lag effect, but the effect of temperature is not obvious. The radial growth of P. euphratica in the section of Aqike was greatly affected by the runoff from January to March. The high temperature in June of that year and November of the previous year became the limiting factor for its radial growth. (3) Sufficient runoff in spring and summer and the autumn of the previous year are the ideal conditions for the radial growth of P. euphratica in the section of Shazihekou. However, in some of these three seasons, the runoff is small and the rest is sufficient. It is still possible to form a wide treering, but if the runoff in these three seasons is not sufficient, narrow treering will inevitably be formed. The ideal condition for the radial growth of P. euphratica in Aqike section is that the lower temperature is more favorable for the radial growth of P. euphratica in the next year when the runoff at the end of autumn is small. The results show that the radial growth of P. euphratica in the middle reaches of Tarim River has a positive correlation response to runoff, a negative correlation response to temperature when runoff is small, and both of them have a lag response.