The invention discloses dihydroxy isoquinoline and a preparation method and application thereof from centipedes, and belongs to the field of medicine. The dihydroxy isoquinoline is 3,8-dihydroxy isoquinoline, is extracted from centipedes and can be used for treating malaria and solid tumors and killing bacteria. The malaria is plasmodium vivax, malaria plasmodium, plasmodium falciparum and plasmodium ovale parasitizing the human body. The bacteria are escherichia coli, staphylococcus aureus, pseudomonas aeruginosa, alpha / beta hemolytic streptococcus, streptococcus pneumoniae and haemophilus influenzae. The tumors are primary or secondary cancers and sarcomas deriving from the head and neck portion, brain, thyroid gland, pancreas, lungs, liver, esophagus, stomach, mammary gland, kidneys, gall bladder, colon or rectum, ovary, uterus, cervix uterus, prostate, bladder and testis of the human body. The dihydroxy isoquinoline has small toxic and side effects, and can be used for treatment and auxiliary treatment of various cancers.