This study aimed to identify heterogeneity in BMI trajectories and evaluate the impact of BMI trajectories on the risk of hypertension in middle-aged and elderly Chinese people. After data screening, 28, 706 residents' e-health records from 2010 to 2018, including basic personal information, lifestyle and health, were finally included in this population-based longitudinal study. By latent class growth modeling, we identified 12 BMI trajectories: "underweight-increase I (A1)" and "underweight-increase II (A2)"; "normal weight-stable (B1)", "normal weight-decrease (B2)", "normal weight-increase I (B3)" and "normal weight-increase II (B4)"; "overweight-stable (C1)", "overweight-decrease (C2)" and "overweight-increase (C3)"; and "obese-stable I (D1)", "obese-decrease (D2)" and "obese-stable II (D3)". By Cox proportional hazards models, we found that the risk of hypertension in the BMI stable group was lower than that in the BMI increasing trajectory group and higher than that in the BMI decreasing group. For the underweight and normal weight groups, the risk of hypertension was related not only to the magnitude of BMI growth, but also to the rate of growth. For overweight and obesity groups, the risk of hypertension was higher in the high-level stable BMI group than in the low-level stable BMI group. Therefore, for underweight and normal weight people, weight growth and growth rate should be controlled; for overweight and obese people, health education or targeted weight loss exercise should be taken to reduce weight as much as possible to prevent hypertension.