Abstract: To address the mismatch between pressure-bearing capacity and lightweight requirements in additively manufactured liquefied gas micro-propulsion tanks, this paper proposes a morphology-based lightweight design method constrained by mechanical performance. Using R134a (tetrafluoroethane) as the propellant and AlSi10Mg as the manufacturing material, a conformal tank system was designed, with the first-stage and second-stage tanks required to withstand pressures of 2 MPa and 1.6 MPa, respectively. High stress concentration and structural redundancy areas were identified using the von Mises equivalent stress method. Morphology optimization with variable thickness was performed with the objective of minimizing stress. The results indicate that with an optimized rib height of 1.6 mm, the maximum stress is 216 MPa, achieving a 37.07% reduction in mass and an 8.6% increase in propellant capacity. Fatigue and ultimate pressure tests were conducted, demonstrating that the tank's fatigue strength meets the 100- cycle requirement and the stages can withstand 2.1 MPa and 1.6 MPa respectively, satisfying the operational requirements for micro-nano satellites.