Objective To examine the associations between the brain-derived neurotrophic factor （BDNF） level， gene polymorphism， and cognitive function in patients with late-life depression. Methods From April 2014 to January 2016， inpatients or outpatients over and 60 years old with first-episode depression from Beijing Anding Hospital affiliated to Capital Medical University were enrolled in this study. The severity of depression and cognitive function were assessed using Hamilton Depression Scale（ HAMD-17）， the verbal fluency test， trail making tests（ TMT） A-B， the Stroop color-word test and Wisconsin card sorting test. Blood samples were collected to determine the level of serum BDNF， and DNA was extracted to determine the single nucleotide polymorphism（ SNP） of BDNF rs6265 gene. Rusults A total of 80 patients were enrolled in this study. No significant associations were found between BDNF rs6265 and the severity of depression（ P＞0.05）. The total score of HAMD-17 was negatively correlated with verbal fluency test and WCST persistent errors（ r= -0.239，-0.226）， and the differences were statistically significant（ P＜0.05）. Patients with VAL/MET on rs6265 performed significantly worse on TMT A-B than that in patients with VAL/VAL（ P＜0.05）. The serum BDNF is not significantly correlated to cognitive function（ P＞0.05）， while it is negatively correlated with the HAMD-17 total score（ P＜0.05）. Conclusions BDNF rs6265 gene polymorphism is associated with cognitive impairment in patients with late-life depression， but not with BDNF level， suggesting that BDNF may affect cognitive function in elderly depression through other mechanisms.