The Cr3+-functionalized additive is tested to overcome the zinc dendrite and hydrogen evolution issue in ZnBr flow battery, which lead to system instability and pH increase of electrolyte. Scanning electron microscopy, X-ray diffraction and high-resolution transmission electron microscopy are investigated to analyze the distribution of electrodeposits. The battery performance is evaluated by the concentration of chromium. As the content of Cr3+ increased, the battery shows higher average coulombic efficiency and the rise rate in the pH of electrolyte has been greatly alleviated. For these reasons, we propose the Cr3+ is the promising additive for dendrite-free and high performance of ZnBr flow battery.