It has a single narrow leaf and up to five yellow flowers with an orange anther and brown arms on the side of the column.

[2][3][4] Thelymitra psammophila was first formally described in 1905 by Cecil Andrews from a specimen he collected near the Kalgan River and the description was published in Journal of the West Australian Natural History Society.

[6]: 355 The sandplain sun orchid usually grows in heath and with sedges in winter-wet areas between the Kalgan River and Ravensthorpe.

[2][3][7][8] Thelymitra psammophila is classified as "Threatened Flora (Declared Rare Flora — Extant)" by the Department of Environment and Conservation (Western Australia) and as "vulnerable" under the Australian Government Environment Protection and Biodiversity Conservation Act 1999.

[7] The main threats to the species are weed invasion, and disturbance from a nearby rubbish tip.