The invention discloses a reusable composite material gas cylinder and a design method thereof. According to the reusable composite material gas cylinder and the design method thereof, through the gascylinder structure form, the raw material selection, the metal inner container design, the composite material layer spreading design, the self-tight pressure design, strength analysis, fatigue life analysis, static analysis and the like, the wall thickness of an inner liner is increased, an inner liner material is improved, a connection layer is arranged between the metal inner liner and a carbonfiber composite material layer, the design that non-destructive testing and health monitoring of a gas cylinder are facilitated is added, accordingly, the technological effects that the long fatiguelife with the reuse number of the gas cylinder being not smaller than 300 is achieved, moreover, the gas cylinder is low in weight, relatively low in economic cost and simple in manufacturing technology, and non-destructive testing and health monitoring are convenient and quick are realized, and the technical effect that the composite material gas cylinder with the long fatigue life is designed isachieved.