See the notes at Exodus 28.
The holy crown - The golden plate of the mitre was so called as the distinctive badge of the high priest’s consecration. See Leviticus 21:12.
Related Commentaries of Leviticus 8:7
Leviticus 8:7-9
7 And he put upon him the coat, and girded him with the girdle, and clothed him with the robe, and put the ephod upon him, and he girded him with the curious girdle of the ephod, and bound it unto him therewith.
8 And he put the breastplate upon him: also he put in the breastplate the Urim and the Thummim.
9 And he put the mitre upon his head; also upon the mitre, even upon his forefront, did he put the golden plate, the holy crown; as the LORD commanded Moses.