Abstract: As a critical load-bearing components in prestressed concrete structures, prestressed steel strands exhibit stress relaxation behavior that directly affects the long-term safety and durability of the structures. Due to the influence of material constitutive properties, manufacturing processes, and service environments, steel strands inevitably experience prestress loss under long-term loading. In recent years, domestic and international scholars have conducted extensive theoretical analyses, experimental studies, and model constructions focusing on the influence mechanisms of factors such as static load, temperature, material composition, interfacial constraints, and fatigue loading on stress relaxation behavior. This paper systematically reviews the stress relaxation of prestressed steel strands under static loading, with emphasis on the effects of initial stress level, temperature, material composition and manufacturing processes on its performance. It further summarizes the action mechanisms of interfacial constraints between steel strands and grouting materials, as well as the effects of strand surface conditions on stress relaxation. Based on this, it analyzes the accelerated evolution characteristics of steel strand stress relaxation under the coupling effects of fatigue loading, fretting wear, and corrosion, as well as their characterization and prediction methods. Finally, in view of the deficiencies in existing studies, this paper prospects the future research trends regarding stress relaxation of prestressed steel strands. This paper can provide a reference for the long-term performance evaluation and durability design of prestressed structures.