The present disclosure provides a display substrate, a manufacturing method thereof, and a display device. The display substrate includes: a backplane; a transistor layer on a side of the backplane; a first planarization layer on a side of the transistor layer away from the backplane; an auxiliary cathode layer on a side of the first planarization layer away from the transistor layer; a second planarization layer on a side of the auxiliary cathode layer away from the first planarization layer; and a light-emitting element layer on a side of the second planarization layer away from the auxiliary cathode layer. The light-emitting element layer includes a primary cathode layer electrically connected to the auxiliary cathode layer.