The present application provides a positive electrode and a lithium-ion battery. The positive electrode comprises a current collector; a first active material layer comprising a first active material; and a second active material layer; wherein the first active material layer is arranged between the current collector and the second active material layer, the first active material layer comprises a first active material, and the first active material is at least one selected from a group consisting of a modified lithium transition metal oxide positive electrode material and a modified lithium iron phosphate. The positive electrode of the present application helps to improve the thermal stability of the lithium-ion battery, and the improvement of the thermal stability may reduce the proportion of the thermal runaway when the lithium-ion battery is internally short-circuited so that the safety performance of the lithium-ion battery is improved.