The invention discloses application of A-nor-5 alpha-androstane compounds in preparation of malignant tumor resistant medicaments. The compounds have the following general formula I, and comprise Ia, Ib, Ic, Id, Ie and If. The growth inhibition rate of the A-nor-5 alpha-androstane compounds for in-vitro human liver cancer cell Hep 3B, human breast cancer MDA-MB-231, human lung adenocarcinoma A549 and mouse melanoma B16 is higher than 85% on average, and even up to 99.98% to the maximum. The in-vivo test proves that the inhibition rate of the A-nor-5 alpha-androstane compounds for mouse tumors, such as intestinal cancer C26, liver cancer H22, Lewis lung cancer, breast cancer, B16 melanoma and the like, is higher than 50% on average, and even up to 63.19% to the maximum. The result proves that the compounds disclosed by the invention have an obvious malignant tumor resistant action. The A-nor-5 alpha-androstane compounds disclosed by the invention have an obvious and broad-spectrum action on inhibiting growth of malignant tumor cells, and are novel targeted malignant tumor resistant medicaments with low drug toxicity and favorable treatment effect; and the A-nor-5 alpha-androstane compounds just specifically act on tumor cells, but not influence normal cells, thereby having a high clinical application value.