Recently, sodium-ion batteries (SIBs), regarded as promising supplements for lithium-ion batteries (LIBs), especially in the large-scale energy storage field, are attracting more and more attention. However, the limited suitable cathode materials hinder the wide commercialization of SIBs. Given this aspect, in this work, a new layered oxide with 4d metal Tin was synthesized and investigated as cathode material for SIBs. Two optimized sodium-deficient O3-Na0.9Ni0.45Sn0.55O2 and O3-Na0.9Ni0.4Mn0.1Sn0.5O2 were selected for comprehensive investigation, both of which exhibited high operating voltage of around 3.45 V with smooth charge/discharge curves. In comparison, O3-Na0.9Ni0.4Mn0.1Sn0.5O2 shows a higher reversible capacity (65 mA h/g, 0.1 C), better rate capability and cycling stability than that of O3-Na0.9Ni0.45Sn0.55O2 (50 mA h/g, 0.1 C), indicating that a small amount of Mn-substitution can improve the electrochemical performance. This work presents a new possibility of discovering potential cathode candidates by exploring the Tin-based layered oxides.