The invention provides a nanometer composite phase-change material, wherein Si element is added into a phase-change material, so that the phase-change material with the reversible phase-change capability is evenly divided into regions with manometer sizes by non-crystalline Si element to form into a binary nanometer composite structure. Furthermore, the invention further provides a method which takes the nanometer composite phase-change material and the optimized nanometer composite phase-change material as the material of a phase-change memorizer. On the one hand, the nanometer structure which is formed by the Si element can improve the crystallizing temperature of the phase-change material, thereby correspondingly improving the retentiveness of date and being good for being intergraded with the CMOS technology; on the other hand, the nanometer structure limits the activity range of the phase-change material in the reversible phase-change process, is good for restraining the component segregation of the phase-change material, and improves the stability of the phase-change material, thereby improving the performance of the phase-change memorizer; and the adding of the Si element can improve the adhesion of the phase-change material and increase the machinability.