The invention discloses a medicine for treating myocarditis and a preparing method and belongs to the field of traditional Chinese medicine. The medicine is prepared from all-grass of filifoliumsibiricum(L.)kitam., fructus mume, purslane speedwell herb, obcordate christia herb, white fungi, manaplant alhagi sweet secretion, common andrographis herb, giant clams, broad beans, canton salomonia herb, Japanese thistle herb or roots, cortex moutan, roots or root bark of hibiscus mutabilis L, orange stonecrop herb and roots, snake gourd fruits and sea clam shells. The medicine has a remarkable treatment effect on myocarditis, and is short in treatment course, fast in effect taking, convenient to take, safe and free of toxic or side effects, relapse does not occur after curing, all the selected medicine materials are in proper compatibility, and the medicine conforms to the traditional Chinese medicine and modern medicine and pharmacology principles, has the effects of dispersing evil and clearing away the heart fire, tonifying the liver and the kidneys, and tranquilizing mind by nourishing the heart, can achieve the purposes of treating both symptoms and root causes, and is low in process, excellent in effect, practical and worthy of wide clinical application and popularization.