Lithium-rich layered oxides have being regarded as one of the most promising cathodes for next generation high energy density lithium ion batteries due to their extremely high capacity beyond 250mAhg−1. Among which, Ru-based lithium-rich layered oxides attract special research interests recently for their relatively low irreversible capacity loss during initial cycle and good rate performance. However, as a typical Ru-based lithium-rich layered oxides, Li2RuO3 suffers severely from poor cycling stability and huge voltage decay upon prolonged cycling. Here, we propose a mono-valence cationic substitution strategy of Na+ ions into Li2RuO3 lattice to form Li2-xNaxRuO3 (x=0, 0.02, 0.06, 0.1) series and systematically investigate their electrochemical properties. The results show that Na+ substitution significantly enhance electrochemical performance of Li2RuO3. Specifically, Li1.94Na0.06RuO3 exhibits the best cycling stability, possessing capacity of over 220mAhg−1 after 50 cycles at 1C rate and retaining energy density of 673Whkg−1 after 50 cycles at 0.2C rate. Li1.9Na0.1RuO3 displays the least voltage decay with only 61mV after 50 cycles compared with 228mV for Li2RuO3. The Na-doped Li2RuO3 samples in this work are leading the electrochemical performance of all ever reported Ru-based lithium-rich layered oxides previously, providing a new scope for the strategy to rationally design high-performance lithium-rich layered oxides with balanced cycling stability and voltage maintainance.