The application discloses a kind of TMD auxiliary installation equipment suitable for narrow space and its construction method, comprising: mobile car, mobile car is equipped with platform plate by electric lifting mechanism, platform plate is movably provided with the bearing platform for TMD to rest, platform plate is connected to bearing platform by electric telescopic arm;Three-dimensional scanning device is installed in bearing platform;Controller, including control module, storage module, modeling module, path planning module, control module is connected to mobile car, electric lifting mechanism, electric telescopic arm and three-dimensional scanning device, storage module, modeling module and path planning module are connected to control module, path planning module is connected to storage module and modeling module.The application solves the problem of narrow construction space and high construction height of existing TMD installation.