The utility model relates to an axle of a heavy-duty truck, in particular to a gas storage axle of a dump truck. The gas storage axle of the dump truck comprises an axle body provided with an inner sealed cavity. The non-pressure-bearing section of the axle body is provided with a gas inlet hole, gas outlet holes and a drain hole, wherein the gas inlet hole, the gas outlet holes and the drain hole are communicated with the inner sealed cavity. The drain hole is located in the side face of the axle body. The inner sealed cavity in the axle body is provided with at least two inner cavity bodies which are independent of each other. The gas outlet hole of each inner cavity body is connected to a main gas outlet pipe in parallel through a gas outlet pipe. Each gas outlet pipe is provided with a one-way valve. According to the gas storage axle of the dump truck, the structure is simple, based on the prior art, a gas chamber is divided into the multiple independent inner cavity bodies which can be connected in parallel, and therefore safety performance is greatly improved.