The present application provides a positive electrode plate, a secondary battery and a power consuming device. The positive electrode plate comprises a positive electrode current collector, a positive electrode film layer provided on at least one surface of the positive electrode current collector, and a conductive undercoat layer between the positive electrode current collector and the positive electrode film layer, wherein the positive electrode film layer comprises a positive electrode active material of a chemical formula of Li a A x Mn 1-y B y P 1-z C z O 4-n D n , and the conductive primer layer comprises a first polymer, a first water-based binder and a first conductive agent.