Abstract: The internal crane type light oil tank car is provided with a new technology of oil loading and unloading under the bottom of tank car. It has such advantages as new type of structure, simple assembling for convenience and low cost of construction. It may relax the working hardship of operating personnel, effectively solve the problem of air resistance during assembly and disassembly, and its technology of oil loading and unloading is more superior than that of present way above the top of tank car.