The invention relates to a high-pressure natural gas long tube trailer for second-level refilling. A pressure container is fixed in a container, a safety relief device is fixed on a rear port of the pressure container in a sealing manner, the safety relief device and a blow-down pipe are fixed through a safety valve in a sealing manner, the safety relief device is communicated with a high-pressure six-way valve through a welding joint, an elbow, a coiler, a three-way valve or four-way fitting in a sealing manner, the high-pressure six-way fitting is communicated with a quick coupler through a welding joint and a ball valve in a sealing manner, the quick coupler is communicated with an air vent valve in the sealing manner, the safety relief device is communicated with a blow down header pipe through a blow off pipe in the sealing manner, two high-pressure gas cylinders are arranged in the pressure container with the pressure of 22MPa, and rest air cylinders in the pressure container are low-pressure air cylinders with the pressure of 18MPa. The high-pressure natural gas long tube trailer overcomes the application limitation of an existing natural gas long tube trailer, successfully integrates storage, transportation and air-entrapping of natural gas into a whole, can be used as a common long tube trailer for the natural gas storage and transportation between a main natural gas station and a branch natural gas station, and can also be used for grading refilling to outside.