Horizontal directional drilling rig is a kind of equipment specially used for underground trenchless construction. Its main functions and applications include: 1. Underground pipeline laying: Horizontal directional drilling rig can lay various underground public facilities such as water supply pipelines, gas pipelines, power cables, communication optical cables, oil and gas pipelines, etc. without excavating the surface. It is particularly suitable for occasions that need to cross roads, railways, rivers, buildings or other ground obstacles. 2. Environmental protection: Due to its trenchless construction characteristics, horizontal directional drilling rigs can greatly reduce damage to the surface, reduce the impact on the environment, and protect the integrity of surface vegetation, roads and buildings. 3. Construction efficiency and precision: This technology has fast construction speed and high precision. It can accurately control the drilling path and depth, reduce construction errors, and improve project quality and safety. 4. Applicable to a variety of strata: It is suitable for geological conditions such as sand, clay, and pebbles. It can be constructed in most non-hard rock areas in my country. Although some information mentions that it is not suitable for high groundwater levels and pebble strata, with the advancement of technology, the adaptability of modern horizontal directional drilling rigs to complex strata has been greatly improved. 5. Economical: Compared with traditional excavation construction, horizontal directional drilling technology can reduce construction costs, reduce the cost of restoring the surface, shorten the construction period, and have significant overall economic benefits. 6. Construction flexibility: The drilling trajectory can be adjusted according to the needs of the project to bypass underground obstacles, which is suitable for arc laying and increases the flexibility of the construction plan. 7. Wide temperature range: The working environment temperature range of the horizontal directional drilling rig is wide, usually -15℃ to +45℃, which is suitable for construction under various climatic conditions. In short, the horizontal directional drilling rig is an indispensable high-end equipment in the construction of modern underground facilities. It realizes fast, accurate and environmentally friendly pipeline laying through trenchless technology, and is widely used in various infrastructure construction projects.