The invention provides a method for cultivating red-pulp hylocereus polyrhizus. The method includes the steps that anthracnose-free hybridized target single plants with the features that the numbers of borne fruits are large in successive years, the weight of single fruit bodies is 400 g or above, the fruit bodies are elliptic, fresh, sweet, elegantly fragrant and good in taste, pulp is bright and rosy, and branches are thick and solid are marked; particularly, branches of the plants in which pistil protrudes out of stamen thrums by 1 cm or less are preferentially and independently collected, sterilized, detoxified and subjected to seedling growing, seedlings are transplanted to land, large-area fruit tree management is carried out, and commercial hylocereus polyrhizus is formed. After three-year intensive-culturing test application, the yield can be continuously high, and the fruits are large and are stabilized to be 0.4-0.5 kg or above; compared with the earlier stage, the fruits are fresher, sweeter and more elegantly fragrant, the shapes of the fruits are not varied and kept elliptic, the content of fructose is about 6.8%, the content of glucose is about 4.2%, and the content of haematochrome is about 4%; other excellent substance characters such as nutrients, the health caring function and the medicine function are not changed, the characters of the original male parent are kept, the hybrid vigor is remarkably expressed, the survival rate is 97% or above, the fruit bearing rate is 95% or above, and the red-pulp rate is 95% or above.