Plants evergreen, large. Rhizome creeping, scales at apex sparse and adpressed; scales dark brown, lanceolate or broadly lanceolate, margin black, small toothed; fronds approximate. Fertile fronds more than 2 m; stipe slightly brown or black-brown at base, upward dark stramineous or green-stramineous when dry, shorter than lamina, 60-90 cm, ca. 1 cm in diam., lower part sparsely scaly; scales similar to those on rhizome apex, deciduous, upward glabrous; lamina 2-pinnate with pinnules pinnatifid to pinnatipartite, ovate-deltoid, 110-120 × 70-80 cm, apex acuminate; pinnae more than 15 pairs, alternate, ascending, apex pinnatipartite, acuminate; lower pinnae oblong-lanceolate or broadly lanceolate, 30-50 × 10-20 cm, pinnate, with stalk 2-5 cm; upper pinnae lanceolate, pinnatilobate or pinnatipartite; pinnules 8-15 pairs, often alternate, spreading or slightly ascending, not contiguous, lanceolate, 3-12 × 1-3 cm, symmetrical or nearly so, base broadly cuneate, shortly stalked, pinnatipartite to pinnatifid, apex caudate; pinnule lobes 8-15 pairs, slightly ascending, not contiguous, margin subentire or few sparsely serrate, apex often rounded; veinlets pinnate in pinnule lobe; veinlets 9 pairs, often simple, rarely forked, ascending, not reaching margin, apex slightly swollen. Lamina thinly herbaceous, green; rachis and costa green-stramineous; costae and costules abaxially with prominent fleshy green aculeate processes, and few brown lanceolate scales, glabrous adaxially. Sori linear, often as long as veinlets, 8 pairs per pinnule lobe, often single or double on basal acroscopic veinlet; indusia brown when mature, membranous, entire. Spores reniform, granular ornamentation on surface.
Wet evergreen broad-leaved forests; 1400-1700 m. SE Yunnan [Vietnam].
Diplazium calogrammum is similar to D. simile but differs by the costa and costule abaxially with many fleshy green aculeate processes.