The embodiment of the invention provides an organic light-emitting diode (OLED) display panel and a fabrication method thereof, relates to the technical field of display and can be used for improving the influence of ambient light on contrast ratio of the OLED display panel. The OLED display panel comprises a display region, wherein the display region comprises a luminous region and a non-luminous region, the luminous region comprises a positive electrode, a negative electrode and an organic material functional layer, the organic material functional layer is arranged between the positive electrode and the negative electrode, the OLED display panel also comprises a dimming structure and a light absorption layer, the dimming structure is arranged in the luminous region and is arranged on a light giving out side, the light absorption layer is arranged in the non-luminous region, the dimming structure is used for irradiating a part of external ambient light incident to the light giving out side of the OLED display panel to the light absorption layer, and the light absorption layer is used for light absorption. By the OLED display panel, the influence of the ambient light on the contrast ratio of the OLED display panel is improved.