The invention discloses a method for increasing single well productivity of an ultra-deep-layer low-permeability heavy oil reservoir. The method comprises steps as follows: a proper reservoir is selected, wherein the reservoir is the ultra-deep-layer low-permeability heavy oil reservoir; a long horizontal well is deployed in an oil layer of the reservoir, wherein the long horizontal well is at least 300 m, so that the contact area of a shaft and the oil layer is increased, and the fluid seepage resistance is reduced; at least three-level staged fracturing is performed on the long horizontal well, and multiple cracks are formed, wherein the cracks are formed by radially outward fracturing extension of the long horizontal well to the oil layer, radial flows are changed into linear flows and pseudo radial flows by the cracks, oil and gas seepage conditions of a near-well zone are improved, pollution to the near-well zone is eliminated, and the single well productivity is increased. With the adoption of the method, the single well productivity of the ultra-deep-layer low-permeability heavy oil reservoir is increased through staged fracturing of the long horizontal well.