The present invention provides a display device and a manufacturing method thereof, including: forming a device board; forming a color resist layer on the device board; forming a black matrix layer on the device board, wherein at least a portion of the color resist blocks is defined in a grid region in the black matrix layer, and at least a portion of an orthographic projection of the color resist blocks on the device board covers at least a portion of an orthographic projection of an adjacent part of the black matrix layer on the device board; and forming a planarization layer covering the color resist blocks and the black matrix layer.