The invention provides a Paris forrestii (Takht) H.Li extract and preparation method or application to preparation of a drug for curing tumors or cancers thereof. The Paris forrestii (Takht) H.Li extract is a rhizome extract extracted with ethyl alcohol. The preparation method comprises the following steps: taking the rhizome of Paris forrestii (Takht) H.Li, drying, soaking for seven days with 95 percent ethyl alcohol after grinding, and filtering; continuously extracting filter residues for four times, merging filtrates, recovering a solvent, and thus obtaining the extract. The Paris forrestii (Takht) H.Li extract has significant inhibitory activity on hepatoma SMMC-7721 cells, lung cancer A-549 cells, breast cancer MCF-7 cells and colon cancer SW480 cells, and the activity is stronger than that of a positive control drug cisplatin. The Paris forrestii (Takht) H.Li extract is a new selection of a drug for curing or preventing cancers.