Provided are a method and apparatus for calculating a volume of a compressed gas storage vessel, a computer, and a medium. According to the method, three test vessels with known volume and initial pressure are used to establish a pressure equilibrium with a compressed gas storage system, and pressure values in three equilibrium states are respectively detected. In this way, according to the three pressure values and the known volumes and initial pressures, a volume of the compressed gas storage system, a volume of a hose, and a pressure value of the compressed gas storage system in an initial state can be quickly and accurately calculated. By accurately obtaining the volume of the compressed gas storage system, the volume of the hose, and the pressure value of the compressed gas storage system in the initial state, a refueling rate can be increased as much as possible while ensuring safe refueling.