Objective To investigate the effect of aging on nutritional status and immunity in patients with hypertension, compare the difference of immune function between aged patients with and without nutritional risk, and analyze the correlations between Nutritional Risk Screening 2002 (NRS2002) and several biochemical parameters. Methods Totally 135 inpatients with hypertension aged ≥ 80 years were recruited as the elderly group, with 146 hypertensive patients aged < 80 years enrolled as the control group. Nutritional risk screening was performed by NRS2002. Cellular immunity and humoral immunity were tested by flow cytometry and scatter turbidimetry, respectively. Hemoglobin (Hb), albumin (ALB), prealbumin (PA), triglyceride (TG), total cholesterol (TC), and high-sensitivity C-reactive protein (hs-CRP) were analyzed in the elderly subjects. Results The proportion of hypertensive patients with nutritional risk in the elderly group was higher than that in the control group (51.85% vs. 30.14%, P < 0.05). Compared with the control group, the proportions of CD3+, CD3+CD4+ and CD3+CD8+ cells were significantly lower (P < 0.05), but the proportion of CD3-CD16+CD56+ cells was significantly higher in the elderly group (P < 0.05). The levels of IgM and B factor were also lower in the elderly group (P < 0.05). However, there was no significant difference in cellular immunity or humoral immunity between the elderly hypertensive patients with nutritional risk and those without nutritional risk. In addition, Hb, ALB, PA and TG were negatively correlated with nutritional risk, while hs-CRP was positively correlated with nutritional risk (P < 0.05). Conclusions In the hypertensive patients of 80 years or older, the nutritional risk is increased, both cellular immunity and humoral immunity are changed, especially cellular immunity is decreased. However, there is no significant difference in immune function among the elderly hypertensive patients with different nutritional risks. Some biochemical parameters, including Hb, ALB, PA, TG and hs-CRP, are correlated with nutritional risk.