The present disclosure relates to a display panel and a manufacturing method thereof, and a display device. The display panel includes a plurality of pixel units. The pixel unit includes a red sub-pixel, a green sub-pixel and a blue sub-pixel. The red sub-pixel, the green sub-pixel and the blue sub-pixel each include a cathode, an electron transport layer, a quantum dot luminescent layer, a hole function layer and an anode that are stacked. The electron transport layer is made of Mg-doped ZnO nanoparticles, and a Mg doping concentration in the electron transport layer of the red sub-pixel, a Mg doping concentration in the electron transport layer of the green sub-pixel and a Mg doping concentration in the electron transport layer of the blue sub-pixel decrease successively.