The invention discloses a preparation technology of full-range of molecular weight tremella polysaccharide. The preparation technology comprises the processes of extracting, removing impurities and decolorizing, performing coarse filtration, performing fine filtration, concentrating, precipitating, performing suction filtration and drying, and is characterized in that the extracting process comprises two extracting steps, namely steam pressure-maintained boiling extraction and high-efficiency enzyme activity accelerant-complex enzyme combined extraction. The preparation technology has the beneficial effects as follows: in the steam pressure-maintained boiling extraction, added polyoxypropylene polyoxyethylene glyceryl ether effectively solves a bubbling problem, and has a significant effect of promoting the enzymolysis efficiency of subsequent acidic protease, cellulase and pectinase; in the complex enzyme extraction, a high-efficiency enzyme activity accelerant is unexpectedly discovered; in the coarse filtration process, an auxiliary agent can not only improve the state of a precipitated material so as to turn the precipitated material into uniformly dispersed fine particles, butalso plays a role in increasing the distillation speed in a next membrane distillation process.