A 3D display method and a display device are provided. The 3D display method includes: adjusting a data line input signal for a 3D display device, so that a black image is displayed on sub-pixel regions of a (4n−2)th (n is a natural number) row and a 4nth row of a display panel of the 3D display device; inputting parallactic image signals for a left eye and a right eye into sub-pixel regions in a (4n−3)th row and in a (4n−1)th row, respectively, so that a left-eye image, the black image and a right-eye image are displayed on the sub-pixel regions in sequence, and each of the sub-pixel regions includes at least one row of sub-pixel structural units.