Traditional space deployable structures predominantly utilize flexible thin-film materials, which suffer from issues such as low structural stiffness after deployment, surface wrinkles, and the need for pressure replenishment to maintain internal pressure. Compared to membrane materials, flexible thermoplastic composites exhibit higher stiffness and strength after molding, better surface quality, and the ability to maintain their shape solely through their inherent stiffness. These characteristics make them highly advantageous and promising for application in the field of space deployable structures. In this regard, the paper focuses on a specific aramid thermoplastic composite and studies its tensile mechanical properties. Firstly, tensile tests are performed on both aramid yarns and the thermoplastic aramid composite to determine the yarn's tensile modulus and strength, as well as the composite's tensile stress-strain curve. Observations indicated that there is a distinct nonlinear characteristic in the stress-strain curve. Subsequently, a unit cell finite element model of the composite is developed. This model employed a micro-mechanical finite element method to simulate the damage progression of the composite under tensile loading. Lastly, a comparison between the predicted stress-strain curve and the experimental results revealed good agreement, validating the accuracy of the simulation methodology, and the simulated damage process illuminated the tensile failure mechanism of the aramid thermoplastic composite. The research results can provide reference for the design and application of flexible thermoplastic composites in space deployable structures.