Hypertriglyceridemia is a common health problem independently associated with an increased risk of atherosclerosis cardiovascular diseases (ASCVD), including ischemic heart disease and stroke. This study aims to determine the prevalence of hypertriglyceridemia among Royal Thai Army (RTA) personnel and its behavioral and cardiometabolic risk factors using the RTA personnel database of the physical health examination from 2017 to 2021. A serial cross-sectional study was conducted from 2017 to 2021. A total of 257,683 active-duty RTA personnel aged 35-60 years were included in the study. We defined hypertriglyceridemia as fasting triglyceride ≥150 mg/dL. Moreover, we performed a multivariable logistic regression analysis to investigate behavioral and cardiometabolic risk factors for the prevalence of hypertriglyceridemia. The magnitude of the association was presented as an adjusted odds ratio (AOR) with a 95% confidence interval (CI). The hypertriglyceridemia prevalence among RTA personnel was 43.4% (95% CI: 42.9-43.8%) in 2017. It then continuously decreased to 40.3% (95% CI: 39.9-40.7%) in 2020 and slightly rose to 41.0% (95% CI: 40.6-41.4%) in 2021 (p for trend < 0.001). The prevalence of hypertriglyceridemia was higher for males than females (AOR 2.15; 95% CI: 2.07-2.23); RTA personnel aged 40-44 years compared with those aged 35-39 years (AOR 1.05; 95% CI: 1.02-1.08); and RTA personnel residing in the northeast (AOR; 1.15 95% CI: 1.11-1.18) and the north (AOR 1.05; 95% CI: 1.02-1.08) compared with those residing in Bangkok. The independent behavioral factors associated with hypertriglyceridemia included alcohol consumption, smoking, and sedentary behavior. Moreover, cardiometabolic risk factors, including higher body mass index, high fasting plasma glucose (≥ 100 mg/dL), high blood pressure (≥ 140/90 mmHg), and hypercholesterolemia (≥ 200 mg/dL), were significantly related to hypertriglyceridemia. Our data demonstrated that hypertriglyceridemia is a frequent health issue, especially among males, participants aged 40-44 years, and RTA personnel residing in the northeast and the north. The prevalence of hypertriglyceridemia in this population was greatly influenced by alcohol consumption, cigarette smoking, and sedentary behavior. Both behavioral and cardiometabolic risk factors are potential targets for intervention to enhance the primary prevention of sequelae of hypertriglyceridemia, including ASCVD.