Abstract: Small modular lead-based reactors with features of compact design and environments of high neutron fluence and high temperature urgently require a structural-functional integrated neutron shielding material that combines good high-temperature mechanical properties and neutron shielding performance. As boron- and gadolinium-containing steels exhibit insufficiency in mechanical properties at high temperature and process-ability, this study selected GdAl₃C₃ cermet as the reinforcing phase and neutron absorber and 316L stainless steel as the matrix in order to develop a GdAl₃C₃-316L shielding material. The GdAl₃C₃-316L shielding material samples with GdAl₃C₃ additions of 0.5%, 1.5%, 3.0% and 5.0% (in weight percentage) were prepared by powder metallurgy. Their micro-structure, tensile properties at room- and high-temperature and neutron shielding performance were systematically analyzed. The results show that chromium-rich phases agglomerate in the material as the GdAl₃C₃ content increases. The formation of a dual-phase structure of ferrite and austenite is promoted in 316L matrix with the solid solution of Al. Furthermore, the GdAl₃C₃-316L samples exhibit a bimodal grain size distribution and the addition of GdAl₃C₃ refined the matrix grains. With GdAl₃C₃ addition among 1.5% to 3.0%, the material simultaneously possesses a high proportion of fine-grained regions (＞82%), a relatively high proportion of high-angle grain boundaries (＞92%), and an appropriate proportion of twin boundaries, achieving a better balance among fine-grain strengthening, ductility coordination, and crack deflection capability. Various in situ formed Gd-Al-O ternary oxides are observed in 1.5%GdAl₃C₃-316L sample, including nanoscale monoclinic Gd₄Al₂O₉ precipitates, submicron simple orthorhombic GdAlO₃ precipitates, and body-centered cubic Gd₃Al₅O₁₂ precipitates, which are dispersed in 316L matrix. The tensile properties at room- and high-temperatures of the samples initially increase and then decrease with the increasing of GdAl₃C₃ content. The 1.5%GdAl₃C₃-316L sample demonstrates good mechanical properties with a yield strength of 696.2 MPa and 613.2 MPa, and an elongation of 22.4% and 14.9% at room temperature and 550 ℃, respectively. The SEM image of the tensile fracture surface of the sample indicates that the material as a whole exhibits ductile fracture characteristic. The neutron shielding experiments show that 3.0%GdAl₃C₃-316L and 5.0%GdAl₃C₃-316L samples achieve a thermal neutron shielding rate of 81.25% and 95.84% at a thickness of 0.9 mm, respectively. The neutron shielding performance of the material is improved with the increase of GdAl₃C₃ content. Compared to Gd-316L alloys with similar gadolinium content, the 1.5%GdAl₃C₃-316L alloy in this study exhibits a better synergy of tensile strength and plastic deformation capability, which indicates its potential for use as a structural-functional integrated neutron shielding material in lead-based reactor.