During the crystallizing process of amorphous melt-spun ribbons of nanocomposite permanent magnetic alloys under normal conditions, α-Fe phase always precipitates preferentially, which will induce coarse grains of α-Fe, and it has been proven to be detrimental to the magnetic properties. To solve this problem, crystallizing behavior and mechanisms of this kind of amorphous melt-spun ribbons under extreme conditions were studied by some researchers recently. In the present paper, these works were reviewed.