Effects of the stability of V+5 electrolyte of the vanadium redox cell has been studied at various temperatures and at different concentration vanadium ion and H2SO4 and solution state-of-charge（SOC）.It has been found V+5 electrolyte temperatures under 45℃and vanadium ion under 1.8mol/L in long time,V+5 can be more suitable in 3mol～4mol/L H2SO4 than 2mol/L.The stability of positive electrolyte of the vanadium redox cell was improved by adding proper additives.
