We determined whether a town-level comprehensive intervention program could lower the salt intake of a population. The parallel, cluster randomized controlled trial was carried out between October 2018 and January 2020 in 48 towns from 12 counties across 6 provinces in China. All participants were asked to complete the 24 h urine collections, anthropometric measurements and questionnaires at the baseline and one-year post-intervention survey. A total of 2693 participants aged 18 to 75 years were recruited at the baseline. A total of 1347 individuals in 24 towns were allocated to the intervention group and the others were allocated to the control group. Valid information from 2335 respondents was collected in the follow-up survey. The 24-h urinary sodium excretion was 189.7 mmol/24 h for the intervention group and 196.1 mmol/24 h for the control group at baseline. At a one-year follow-up, the mean effect of salt intake did not show a significant change (p = 0.31) in the intervention group compared to the control group. However, the mean result of potassium excretion in the intervention group increased by 2.18 mmol/24 h (85.03 mg/24 h) (p = 0.004) and systolic blood pressure decreased by 2.95 mmHg (p < 0.001). The salt-related knowledge and attitude toward salt reduction improved significantly in the intervention group (p < 0.05). A longer period of intervention and follow-up assessment might be needed to evaluate the long-term effectiveness of the program on salt reduction.