The invention discloses the use of a substance for inhibiting the gene expression and/or protein activity of type C ClassINiemann-Pick protein (NPC1). The use is selected from at least one of the group consisting of (a) a medicament for preventing and/or treating cancer; (b) the medicament for preventing and/or treating cancer diffusion metastasis; (c) the medicament for preparing apoptosis promoting cancer cells; (d) the medicament for preparing cancer-inhibiting cancer cells; (e) the medicament for preparing inhibition of the proliferation of cancer cells in vitro. The present inventors haveproved that Type C Class 1 Niemann-Pick protein (NPC1) is highly expressed in liver cancer tissues, and the abundance is high, and the prognosis of patients with liver cancer is poor. Type C Class-1Niemann Pick protein (NPC1) inhibitor can effectively inhibit the growth of human liver cancer and other tumor cells at the cell level, and can be used as a candidate medicine target for tumor, especially liver cancer.