The present invention provides a mask structure and a COA type array substrate. The mask structure comprises a central light shielding portion (1), a peripheral light shielding portion (3) surrounding the central light shielding portion (1) and conforming to an outer contour shape of the central light shielding portion (1) and a circumambient hollow slit (5) sandwiched between the peripheral light shielding portion (3) and the central light shielding portion (1). The exposure light will diffract through the hollow slit (5) to result in the propagation of the reverse bending and the energy intensity gradient. In conjunction with the negative photoresist, the taper of the finally manufactured color filter layer through hole can be made to be gentle to improve the electrical connection quality between the pixel electrodes and the metal material signal lines for avoiding the display failure.