Mars is believed to contain signs of the ancient life and to be the future of humankind. Deep space explorations on Mars have received extensive attention from the scientific and engineering communities. An ancient papyrus scroll-inspired mechanism to deploy the national flag after landing is proposed in this paper. Firstly, a papyrus scroll-inspired structure folded and deployed by shape memory polymer composites (SMPCs) was designed. The material was characterised by both thermodynamic analysis and static mechanical tests. Then, computational modal analysis was completed with material parameters at 25 °C, 55 °C and 85 °C to investigate the temperature effect. Besides, ground-based engineering validations were conducted, including vibration, shock and acceleration tests, as well as deployment verification. Natural frequencies obtained from vibration agreed well with that calculated from simulation. Regular and vacuum deployments showed differences but were both acceptable. Additionally, release reliability greater than 99.99% was obtained through repeated experimental data. Finally, on-Mars qualification was completed with China’s Tianwen-1 mission, with images of the deployed five-star red flag transmitted by the Zhurong rover. It is the world’s first validation of self-deployable mechanism based on SMPCs in deep space, and further applications can be expected.