Objective To investigate the effect of high-frequency repetitive transcranial magnetic stimulation（rTMS）on elderly patients with depression and mild cognitive impairment. Methods Totals of elderly 48 patients with depression and mild cognitive impairment were randomly divided into control group and experimental group. Four weeks of 20 Hz rTMS was conducted in experimental group. Hamilton Depression Scale（HAMD），Mini-mental State Examination （MMSE）and event-related potentials P300 were examed before treat-ment，after treatment and after 3 months. Results After treatment and after 3 months，HAMD scores of exper-imental group were significantly lower than that of control group （t=-3.711，P=0.001；t=-3.978，P＜0.01），while MMSE scores were significantly higher than that of control group （t=2.705，P=0.01；t=2.934，P=0.006）. After treatment and after 3 months，amplitude of P300 on Fz and Cz was significantly larger （P＜ 0.01），while latency of P300 was significantly shorter in experimental group than that of control group（P＜0.05）. Conclusions Highfrequency rTMS could improve depressive emotion and cognitive function in elderly patients with depression and mild cognitive impairment.