The present disclosure discloses a quantum dot light-emitting diode and a preparation method therefor, wherein the quantum dot light-emitting diode comprises an anode, a cathode, and a quantum dot light-emitting layer disposed between the anode and the cathode, further includes a first modified layer disposed between the anode and the quantum dot light-emitting layer, comprising PAMAM having transition metal cation doped. The present disclosure, by disposing the first modified layer between the anode and the quantum dot light-emitting layer to modify the anode, is able to increase work function of anode, thereby improving hole injection effect and performance of a device. The present disclosure, by disposing a second modified layer between the cathode and the quantum dot light-emitting layer to modify the cathode and reduce the work function of the cathode, thereby improves electron injection effect and performance of the device.