P2-type layer oxides are one class of cathode materials for Na-ion batteries (SIBs) with the advantages of good rate and cycle performance, but suffer from poor storage stability and relative low capacity, hindering their practical applications. In this study, the Mg/Ti co-substituted P2-type layered oxide Na0.67Ni0.23Mg0.05Ti0.05Mn0.67O2 (NMgTiM) was synthesized via sol–gel method. The initial capacity of NMgTiM reached to 162.2mAh g−1, which is more than twice that of pristine oxides Na0.67Ni0.33Mn0.67O2 (NM), showing an excellent synergistic effect. Long-cycle testing showed that the NMgTiM delivered a high and stable capacity of 165 ∼ 180mAh g−1 at 0.5C before 80 cycles, and remained at 132.6mAh g−1 with a capacity retention of 81.6 % at 100th cycle. The crystal structure of pristine and Mg/Ti substitution samples was confirmed by XRD analysis.