An organic light-emitting diode (OLED) display screen and an OLED display device are provided. The OLED display screen has a first display region, a second display region, and a folded display region. A bonding region is disposed on a side edge of the second display region away from the folded display region. Only part of a first backplate disposed on the second display region close to the bonding region is retained and replaced with a buffer layer to ensure stability of a shape of the folded display region and prevent wave warping.