Zinc-based batteries have high theoretical specific capacity and low production cost, but the formation of Zn dendrites limits its practical application in aqueous batteries. In this work, a new method for Zn dendrite suppression by external magnetic field is proposed. Under the interaction of magnetic field and electric field, Zn ions are affected by Lorentz force and spiral motion, which produces disturbance to the electrolyte and promotes the mass transfer process on the electrode surface. This process promotes the mass transfer process on the electrode surface, makes the distribution of zinc ions more uniform, reduces the concentration polarization, and effectively inhibits the growth of zinc dendrites. The electrochemical performance test results show that the magnetic field effect can effectively reduce the nucleation overpotential of Zn and prolong the cycle life. This new method of Zn dendrite suppression by applying magnetic field to the outside of the cell without modifying the inside of the cell has a very wide range of research and application value.