Embodiments of the present application provide a lithium metal negative electrode, a preparation method therefor and related lithium metal battery and device. The lithium metal negative electrode may comprise: a negative electrode current collector; at least one lithium-based metal layer provided on at least one surface of the negative electrode current collector; and an ion-conducting polymer modification layer, which is located on the surface of one of the at least one lithium-based metal layer and comprises at least catalytic amount of a Lewis acid, the Lewis acid containing cations of a metal capable of forming an alloy-type active material with lithium.