The present invention provides a mounting structure for a compressed gas storage tank of a vehicle in which at least two high pressure storage tanks are modularized and mounted in a vehicle.For this, the present invention provides a mounting structure for a compressed gas storage tank of a vehicle, comprising: a plurality of storage tanks for storing a compressed gas therein, including a hemispherical dome portion formed on both ends thereof; panel brackets connected to both ends of the storage tanks; pipe frames connecting edges of the panel brackets connected to both sides of the storage tanks; and high pressure parts and pipes connected to the storage tanks in a state where the panel brackets and the pipe frames are connected.