Abstract: The sodium-cooled fast reactor (SFR) has the functions of nuclear fuel breeding and transmutation of long-lived minor actinides, and it is one of the main recommended reactor types for the fourth-generation nuclear energy systems. The realization of the functions and performance advantages of the SFR mainly depends on the core design. The SFR has already shown a trend towards large-scale and commercial application. Based on the analysis of the connotation of the SFR core design and existing design practices, this paper focused on improving the economy, safety, and sustainability of the SFR, and studied and proposed directions and measures for core design optimization. These include: targeting the increase of fuel burnup limit, the average discharge burnup of fuel, and the flattening of core coolant outlet temperature to enhance economy; targeting the optimization of negative reactivity feedback effects, the improvement of reactivity control performance, and the optimization of natural circulation design to enhance safety; and targeting the improvement of nuclear fuel breeding and the transmutation capability of long-lived minor actinides to enhance sustainability. The proposed directions and measures for core design optimization can serve as the goals and main content for the research and development of SFR core design.