The present disclosure provides a positive electrode of lithium-ion battery, an all-solid-state lithium-ion battery and a preparation method thereof, and an electrical device. The all-solid-state lithium-ion battery of the present disclosure includes a positive electrode, a solid electrolyte, and a negative electrode; wherein the positive electrode includes a positive electrode current collector and a positive electrode material layer provided on a surface of the positive electrode current collector, a positive electrode active material in the positive electrode material layer is a manganese oxygen compound; and the negative electrode includes a negative electrode current collector and a negative electrode material layer provided on a surface of the negative electrode current collector, a negative electrode active material in the negative electrode material layer is a titanium oxygen compound.