Abstract: Used as an additive for the negative electrolyte of vanadium battery,the effects of Na₂MoO₄ on electrochemical performances and stability of the electrolyte,and properties of the battery were studied. The results indicate that electrochemical activity of the negative electrolyte and diffusion coefficient of V（Ⅲ） species can be enhanced by adding Na₂MoO₄,with the charge transfer resistance decreased. The stability of negative electrolyte at low temperatures can not be affected when 0 ~1. 5% of Na₂MoO₄ is added. Compared with the battery without adding Na₂MoO₄,capacity and energy of the battery added 1. 0% of Na₂MoO₄ are increased to a certain extent. Especially,the discharge capacity and discharge energy at 120 mA/cm² for the battery with adding 1. 0% of Na₂MoO₄ are increased by 25. 59% and 21. 89%,respectively.