ABSTRACT Advanced polymeric composites and manufacturing techniques promote developments of marine structures significantly (e.g., spare parts supply chain of shipbuilding and maintenance). In this paper, the GNP/CF-PPS (graphene nanoplatelets short carbon fibre polyphenylene sulfide composite) samples are prepared by mechanically mixing CF-PPS plastic pellets and GNP particles. The mixed compound is 3D-printed by material extrusion additive manufacturing, and the bending mechanics test is carried out to explore how nanoreinforcement affects the ability of printed composites to perform under high temperature conditions. The results show that CF-PPS and GNP/CF-PPS samples have the highest flexural strength at room temperature. As the temperature rises to 260°C, the stiffness increases by 4.8% and 6.7% respectively, while the deflection decreases by 30.4% and 25.6% respectively. The characterisation results of scanning electron microscopy (SEM) show that the cross-sectional pores of CF-PPS samples after adding GNP are relatively reduced, indicating the improvement in the structural stability.