[Objective] The impact of tunnel construction on soil organic carbon content and enzyme activity in the Qinghai-Xizang Plateau was researched in order to provide a theoretical reference for elucidating the impact of tunnel construction on the ecological environment. [Methods] Based on the construction of a tunnel project on the Qinghai-Xizang Plateau, fixed monitoring plots with a radius of 10 m were set up in the impact area and control area of tunnel construction to study the short-term effects of tunnel construction on surface soil organic carbon content and enzyme activity. [Results] After one year of tunnel construction, the soil organic carbon content, easily oxidizable organic carbon content, and soluble organic carbon content in the tunnel-impact area were determined to be 76.84, 25.90, and 3.15 g/kg, respectively, while that of the control area was 52.91, 15.60, and 3.18 g/kg, respectively, whereas that after three years of tunnel construction was 92.63, 28.65, and 3.41 g/kg in the impact area respectively, and 94.81, 23.11, and 3.34 g/kg in the control area, respectively. The differences were not significant (p＞0.05), indicating that tunnel construction has no impact on soil organic carbon and component content in the short term. The activities of β-glucosidase and catalase in the soil of the tunnel-affected area demonstrated no significant differences compared to the control area after one year and three years of construction (p＞0.05), while the activity of polyphenol oxidase in the tunnel-impact area decreased significantly after one year of construction (p=0.02). However, after three years of construction, there was no significant difference in polyphenol oxidase activity between the tunnel-impact area and the control area (p＞0.05), indicating that tunnel construction had no significant effect on soil enzyme activity. [Conclusion] Tunnel construction has no significant impact on soil organic carbon and its component content, as well as enzyme activity in the short term. This is primarily because the tunnel construction process has no significant impact on soil microbial processes, soil nutrients, and input and output of soil organic carbon, while the long-term impact needs further research.