Objective: To observe the effect of hypoxia on the liver function of constructors at high altitude. Method: Select 221 constructors aged 23～42 as subjects, who had worked for 3～6 months at 4500 m. Collect venous blood from fasting subjects and determine GPT by new Lai’s Method from “The Nationwide Clinical Inspection Operating Rules“. Results: The study indicated that the GPT of 45 subjects among Group 1 were abnormal, with the proportion of 20.3%. The peak of GPT appeared when subjects exposed to high altitude of 4500m for 1 month, and the mean value was 83.76±9.23.The GPT of workers were higher than that of administers at different altitude (p<0.05). And the GPT of subjects at 4500 m were higher than those at 3500 m (p<0.05). We can find a degrading tendency with the increasing of working time (p<0.05). There was significantly statistic difference between two groups. Conclusions: The study confirmed that hypoxia could cause the change of liver function mildly and moderately. And there was a positive correlation between the degree of hypoxia and liver function. But, the change began to become a decreasing trend when people went on working longer. We also found that the change of liver structure and function at high altitude correlated with several factors else, including labor, individual difference, methods and sensitivity to the test. However, the explanation of its key mechanism deserves further investigation. Objective: To observe the effect of hypoxia on the liver function of constructors at high altitude. Method: Select 221 constructors aged 23 ~ 42 as subjects, who had worked for 3 ~ 6 months at 4500 m. Collect venous blood from fasting subjects and determine GPT by new Lai’s Method from ”The Nationwide Clinical Inspection Operating Rules". Results: The study indicated that the GPT of 45 subjects among Group 1 were abnormal, with the proportion of 20.3%. The peak of GPT appeared when subjects exposed to high altitude of 4500 m for 1 month, and the mean value was 83.76 ± 9.23. The GPT of workers were higher than that of administers at different altitude (p <0.05). And the GPT of subjects at 4500 m were higher than those at 3500 m (p <0.05). We were found statistically significantly different between two groups. Conclusions: The study confirmed that hypoxia could cause the change of liver function mildly and moderately . And there was a positive correlation between the degree of hypoxia and liver function. But, the change began to become a decreased trend when people went on working longer. We also found that the change of liver structure and function at high altitude correlated with several factors else, including labor, individual difference, methods and sensitivity to the test. However, the explanation of its key mechanism deserves further investigation.