The invention provides a method for adjusting a display parameter, wherein the method is applied to a display device. The method comprises the steps of detecting a second illumination brightness valuein a current environment; acquiring a first illumination brightness value in a previous detection environment, and acquiring a first display value corresponding to the first illumination brightness value; calculating a second display value in the current environment according to the first illumination brightness value, the second illumination brightness value and the first display value; according to the calculated second display value, adjusting the display parameter of the display device from the first display value to the second display value. The invention further provides a display device. The display parameter of the display device can be automatically controlled according to the change of the ambient brightness. Therefore, the display parameter of the display device is maintained within the comfortable experience range of users.