Cirsium japonicum is a perennial herb with a height of 60- 1.20 cm. The stem is erect and stout, and the upper part is densely covered with spider silk. The lower and middle leaves of the stem are lanceolate or round-lanceolate, sessile, ear-shaped, pinnately cleft, with wide triangular lobes, teeth with the same size at the edge, thorns 5- 15mm long, green on both sides, yellow needles with sparse growth of 3-8mm in the upper part, and pilose veins in the lower part; The upper leaves are strip-lanceolate with sparse teeth. The head is solitary or 1-2 clustered at the branch end, spherical, 4-5 cm in diameter, sessile or short-stalked, with bract leaflets at the base; The involucre is densely covered with spider silk fluff; The outer involucral bracts and the middle involucral bracts are oval, with narrow apex, ridges on the back, long inner layer and long conical apex; All of them are tubular flowers, the corolla is dark purple, about 3.8cm long, and the tube length is about twice as long as the eaves. Achene oblong 4.5-7 mm, flat, light brown-black, slightly brighter; The crest is feathery, dirty white and slightly rough at the top.