It has up to fifteen dull greenish, pinkish or brownish flowers with red lines and a labellum with a purplish "beard", but is leafless.

Calochilus pruinosus is a terrestrial, perennial, deciduous, herb with an underground tuber but is leafless.

[2][3][4][5] Calochilus pruinosus was first formally described in 2006 by David Jones and the description was published in Australian Orchid Research from a specimen collected near Hopetoun.

[5][7] The mallee beard orchid grows in woodland in coastal areas between Hopetoun and Eyre in the Esperance Plains and Hampton biogeographic regions.

[2][5][8] As of 2011, C. pruinosus is only known from three sites near Hopetoun, although there are historical records from south of the Stirling Range and near Eyre.