A sub-pixel arrangement structure, a mask device, and a display device are provided. The sub-pixel arrangement structure includes: a reference sub-pixel array, a plurality of third sub-pixels, and a plurality of fourth sub-pixels. In the reference sub-pixel array, each row of sub-pixels or each column of sub-pixels includes: first sub-pixels and second sub-pixels, both of which are arranged alternately; in either or both of first and second directions of the sub-pixels in the reference sub-pixel array, one of the third sub-pixels is arranged between any two adjacent sub-pixels in the reference sub-pixel array; and one of the fourth sub-pixels is arranged among any four adjacent sub-pixels in the reference sub-pixel array, and a center of the one of the fourth sub-pixels is located between two rows of sub-pixels of the four sub-pixels arranged in two rows and two column.