The present application relates to the field of electrochemistry, and in particular to a positive electrode sheet for a secondary battery, a secondary battery, a battery module, a battery pack and a device. The present application provides a positive electrode sheet for a secondary battery. The positive electrode sheet comprises a positive electrode current collector and a positive electrode active material layer located on the surface of the positive electrode current collector; the positive electrode active material layer comprises positive electrode active materials, the positive electrode active materials comprise a first lithium nickel transition metal oxide and a second lithium nickel transition metal oxide, the first lithium nickel transition metal oxide comprises a first substrate and a first coating layer located on the surface of the first substrate, the first substrate is secondary particles, and the second lithium nickel transition metal oxide is particles having monocrystalline or monocrystalline-like morphology. In the positive electrode sheet provided by the present application, by adjusting and controlling the particle size distribution of the positive electrode active materials after mixing and an OI value of the electrode sheet, the compressive strength of positive electrode active material particles in the positive electrode sheet is increased, and the problem of particle cracking of the positive electrode active material particles is effectively restrained.