An organic light emitting diode (OLED) display device and a display panel thereof are provided. The organic light emitting diode display panel comprises a first substrate, a first electrode, an organic light emitting layer, a second electrode, and a second substrate. The first electrode is disposed on the first substrate. The organic light emitting layer is disposed on the first electrode. The second electrode is disposed on the organic light emitting layer. The second substrate is located on the second electrode. The material of the second electrode comprises an alkaline earth element and silver. The second electrode comprises a first portion and a second portion, and the first portion is located between the second portion and the first substrate. The ratios of the alkaline earth element to silver in the first portion and in the second portion are different.