Abstract: The installation technology experience in large diameter pipeline in mountain steep slope areas is relatively less, and the gradient and length of Weijiabao Reroute Section in Sichuan Gas-to-East Gas Pipeline Project are especially rare in China. Taking the pipeline installation in steep slope area in the Section as an example, the installation technique for large diameter pipeline are analyzed and summarized in terms of the difficulty in installation technique, operation scheme selection and technical features, etc. Right of way leveling, ditch digging, pipe corridor cleaning and the requirements in personnel safety and protection are provided in details during excavating in mountain steep slope areas. This technology can help researchers to further explore the feasibility in installation technology for large diameter pipeline in mountain steep slope areas. It plays a guiding role in similar operation condition and also provides a reference for small diameter pipeline installation in mountain steep slope areas.