Objective To investigate the prevalence and risk factors of hypertension in young men first exposed to high altitude for half a year at 4500 m. Methods A total of 228 young men who firstly traveled from a plain area to an altitude of 4500 meters in northern Tibet and stayed there for six months were recruited in present study. They were divided into hypertension group (HTN, n=66) and non-hypertension group (NTN, n=162) based on their blood pressure status. A self-administered questionnaire, the Pittsburgh Sleep Quality Index (PSQI), physical examinations and laboratory tests were used to investigate the risk factors and clinical complications of hypertension. The general data and clinical complications of the two groups were compared, and multivariate logistic regression was used to analyze the risk factors of high-altitude hypertension and predisposition of clinical complications. Results Among the 228 individuals, 66 developed hypertension (incidence of 28.9%), including 52 cases of stage Ⅰ hypertension and 14 cases of stage Ⅱ hypertension. Fifty-eight individuals had isolated diastolic hypertension, and 8 individuals had combined systolic and diastolic hypertension. The proportions of obesity and overweight, central obesity, smoking over 10 cigarettes per day, family history of hypertension, dyslipidemia, and hyperuricemia were significantly higher in HTN group than those in NTN group (P<0.05). The PSQI score was also higher significantly in HTN group than that in NTN group (P<0.001). Multivariate logistic regression analysis showed that hyperuricemia (P=0.02), central obesity (P=0.04), family history of hypertension (P=0.03) and sleeping quality (P<0.001) were the independent risk factors for high-altitude hypertension. The proportion of clinical complications in the past month in HTN group was significantly higher than that in NTN group (P=0.001), and the proportion of three or more kinds of clinical complications was also higher in HTN group than that in NTN group (P=0.01). After adjusting for demographic differences, the risk of dizziness and headache in HTN group was higher than that in NTN group (P<0.05). Conclusions Young men firstly exposed to an altitude of 4500 meters still have a high incidence of hypertension after six months, mostly stage Ⅰ hypertension with diastolic pressure elevation; Hyperuricemia, central obesity, family history of hypertension, and poor sleep quality are the independent risk factors for high-altitude hypertension. High-altitude hypertension can cause various clinical complications, and the higher risk of accompanying dizziness and headache.