In view of the harsh use environment and narrow operation space of a missile launcher, in order to solve the problems of air supply and replacement process in the maintenance of the missile at present, and the difficulty in accurately controlling nitrogen pressure, and to meet the requirements of air supply and replacement of the missile in remote and harsh environments, a portable intelligent nitrogen charging device is designed. By adopting PLC automatic control technology and intelligent sensing measurement technology, The requirement of air supply and replacement technology for missile launcher is realized, and the automation degree of barrel maintenance is effectively improved. The equipment can automatically calculate the theoretical pressure inside the launcher according to the external atmospheric pressure and temperature. The test proves that the equipment can meet the design requirements according to the design process, and the actual inflation pressure and theoretical inflation pressure error meet the design requirements. At present, the equipment has been equipped with several types of barrel bombs for barrel maintenance in remote environmental areas.