Abstract: Objective To investigate the effect of obstructive sleep apnea-hypopnea syndrome (OSAHS) on heart rate variability in elderly patients with hypertension. Methods Eighty elderly patients with hypertension in our hospital from March 2015 to September 2016 were divided into two groups, OSAHS group (38 cases) and non-OSAHS group (42 cases). Another 30 healthy volunteers were selected as healthy control group. Three groups were examined by 24-hour dynamic electrocardiogram to obtain HRV time-domain index data and frequency-domain index data. Results ① The indexes of SDNN, SDANN and rMSSD in non-OSAHS group were (118.15±15.64) ms, (121.55±16.55) ms, (27.98±10.29) ms, respectively, lower than those in control group (all P<0.05); the indexes of SDNN, SDANN and rMSSD in OSAHS group were (89.19±13.95) ms, (86.64±17.34) ms, (21.44±7.27) ms, respectively, which were lower than those in non-OSAHS group (all P<0.05). ② The LF indices of the three groups were (20.01±7.99) Hz, (21.56±8.96) Hz, (21.63±9.33) Hz (P>0.05). The HF index of non-OSAHS group was (11.32±4.56) Hz, lower than that of control group [ (14.75±5.19) Hz], P<0.05; the HF index of OSAHS group was (9.14±3.82) Hz, lower than that of non-OSAHS group (P<0.05). The L/H index of non-OSAHS group was (1.96±0.34) Hz, higher than that of control group [ (1.45±0.38) Hz], P<0.05; the L/H index of OSAHS group was (2.23±0.32) Hz, higher than that of non-OSAHS group (P<0.05). Conclusion OSAHS can reduce the HRV index of elderly patients with hypertension, aggravate the degree of sympathetic and parasympathetic imbalance, increase the sympathetic nerve tension, and aggravate the adverse prognosis of elderly patients with hypertension.