Catholyte stability of VRB was studied by adding additives in the negative vanadium sulfate solution. The V(Ⅲ)sulfate solutions properties with 1% oxalic acid,ammonium oxalate,ethylene diamine tetraacetic acid,glucose,D-fructose and α-lactose were investigated by using cyclic voltammetry and AC impedance. The experimental results showed that the solubility and stability of V(Ⅲ)solution were improved. The solution containing a small amount of carboxylic acids was better than that containing hydroxyl compounds. The charge-discharge performance of the VRB(1.8 mol·L-1 V3+ sulfate solution with 1% oxalic acid as catholyte and 2 mol·L-1 VOSO4-H2SO4 solution as anolyte)had the higher unit volume capacity.