Disclosed are a method for color complementation on a white organic light emitting diode (WOLED) display device, and a display device. The method comprises: (a) acquiring respective first chromaticity coordinates of each of red (R), green (G), blue (B), and white (W) sub-pixel units for a brightness outputted by the WOLED display device; (b) calculating a first complementary color ratio among the R, G, B, and W sub-pixel units; (c) determining a desired brightness of the W sub-pixel unit, and obtaining respective first complementary color brightnesses of each of the R, G, B, and W sub-pixel units, and in turn determining respective second chromaticity coordinates of each of the R, G, B, and W sub-pixel units corresponding to the respective first complementary color brightness of each of the R, G, B, W sub-pixel units; and (d) implementing in iterations steps (a), (b) and (c), so as to obtain a second complementary color ratio among the R, G, B, W sub-pixel units corresponding to the desired brightness of the W sub-pixel unit. Color complementation of the WOLED display device is carried out depending on the second complementary color ratio among the R, G, B, and W sub-pixel units when the brightness outputted by the WOLED display device reaches the desired brightness of W sub-pixel unit.