This study presented an improved CTAB method for extracting DNA from leaves of Populus euphratica Oliv. and Populus pruinosa Schrenk. based on the conventional CTAB method. The results showed that preventing DNA from browning is a key step to obtain the high-quality DNA during DNA extraction, and under the condition of grinding in the presence of liquid nitrogen, adding such three antioxidants as PVP dry powder, Vc and β-mercaptoethanol could prevent DNA from browning effectively. The total DNA extracted by the improved CTAB method was subjected to PCR detection which proved that it totally satisfied the requirements of subsequent study.