The invention relates to a traditional Chinese medicine preparation, and in particular relates to grass oil for treating arthritis and traumatic injury. The grass oil is prepared from the following traditional Chinese medicine raw materials: 50g of codonopsis pilosula, 40g of Chinese actinidia root, 40g of eucommia ulmoides, 15g of rhizoma cyperi preparata, 40g of fructus lycii, 15g of rhizoma corydalis, 50g of Chinese angelica, 35g of rhizoma ligustici chuanxiong, 40g of herba cistanche, 30g of rehmannia glutinosa, 30g of morinda officinalis, 30g of creeping oxalis, 12g of rhizoma coptidis, 20g of frankincense, 15g of radix astragali, 20g of myrrh, 20g of liquorice, 35g of radix achyranthis bidentatae, 45g of cortex acanthopanacis, 20g of safflower, 15g of aralia chinensis, 30g of radix salviae miltiorrhizae, 35g of radix aconiti preparata, 30g of herba lycopi, 35g of radix aconiti kusnezoffii preparata, 40g of herba asari, 40g of radix cynanchi paniculati, 30g of nidus vespae, 30g of rhizoma atractylodis macrocephalae, 25g of radix clematidis, 30g of fructus xanthii, 35g of folium artemisiae argyi, 30g of radix linderae leaves, 35g of argy wormwood leaf and 30g of red dates. The grass oil provided by the invention has a scientific formula and realizes an obvious curative effect on treating arthritis and traumatic injury.