Abstract: The O3-type NaNi1/3Fe1/3Mn1/3O2 (NFM111) serves as an excellent cathode material for sodium-ion batteries, thanks to its outstanding performance at both high and low temperatures, as well as its impressive specific capacity. However, poor cycling due to high-pressure phase transition remains a disadvantage. Herein, Cu/Ti is introduced into NFM111 cathode material by solid-phase method. Combining theoretical and experimental studies, this study discovers that Cu doping provides a higher redox potential, improving the reversible capacity of the material and charge compensation process. The introduction of Ti can enhance the cycling stability of the material, smooth the charge and discharge curves, suppress the high-voltage phase transition. Consequently, NaNi0.27Fe0.28Mn0.33Cu0.05Ti0.06O2 sample exhibits remarkable rate performance of 142.97 mA h g-1 at 0.1 C (2 - 4.2 V) and excellent capacity retention of 72.81% after 300 cycles at 1 C.