This application provides a composite positive electrode material and a preparation method thereof, a secondary battery, a battery group including the secondary battery, and an electric apparatus including the secondary battery. The composite positive electrode material includes a lithium-rich metal oxide and a positive electrode active material covering at least a partial surface of the lithium-rich metal oxide, where the positive electrode active material is formed through in-situ reaction between a positive electrode active material precursor and a free lithium compound on the surface of the lithium-rich metal oxide.