Eragrostis leptophylla is a densely tufted perennial grass that grows 60 to 100 cm tall. The erect, slender culms are glabrous and support narrow, upright leaves. Leaf blades are involute, measuring 10–25 cm in length and only 1–2 mm wide. The upper surfaces are villous near the base and scaberulous near the apex, while the lower surfaces are glabrous. Sheaths are longer than the internodes (5–10 cm), glabrous except for pilose hairs at the throat, ciliate margins, and pubescence on the collar. Ligules are short (0.2–0.5 mm) and ciliate. Stipules are absent. The inflorescence is a slender, spike-like panicle, typically dense, measuring 15–30 cm in length and 0.5–0.8 cm in width. Both the panicle axis and pedicels are scabrous or puberulent. Spikelets are 4–10-flowered and range in length from 4 to 9 mm. The rachilla is sparsely pilose. Glumes are narrow, subequal (3–5 mm), and either as long as or longer than the first floret. The first glume is 1-nerved, and the second is 3-nerved, both tapering to an attenuate apex with scaberulous keels near the tip. Lemmas are 2–3 mm long, imbricate, faintly 3-nerved, and minutely scaberulous along the keel; the apex is acute. Paleas are 1.7–2 mm long with scaberulous keels and usually truncate, erose apices. The fruit is a narrowly ovoid, dark red caryopsis, 0.7–1 mm long and finely rugose. It is found in exposed habitats, including grasslands, dry forests, subalpine forests, and subalpine shrublands, often in sandy soils between 360-2,140 meters.