NOVELTY - Microwave-assisted extraction of monomer ginsenosides Rg3 and Rh2 from ginseng, comprises: crushing ginseng raw material into coarse powder, soaking in ethanol solution, conducting microwave extraction 2-4 times, filtering the extract, mixing the filtrates, and conducting vacuum distillation to obtain crude extract of total ginsenoside, adding water, heating, filtering, washing the filtrate to obtain fine total ginsenosides; separating panaxadiol and panaxatriol total saponin; and degrading panaxadiol saponin to obtain a mixture containing ginsenosides Rg3 and Rh2.    USE - The method is useful for microwave-assisted extraction of monomer ginsenosides Rg3 and Rh2 from ginseng (claimed).    ADVANTAGE - The method has short extraction time, reduces the use level of solvents and the energy consumption, and meanwhile improves the ginsenoside yield. The ginsenoside monomers Rg3 and Rh2 are purified by adopting a macroporous resin adsorption and normal pressure silica-gel column separating method, so that the method is simple to operate and high in product yield and purity. Methanol is re-crystallized, so that the product purity is improved, the energy consumption is less, and the method is convenient to operate.    DETAILED DESCRIPTION - Microwave-assisted extraction of monomer ginsenosides Rg3 and Rh2 from ginseng, comprises: (i) preparing total ginsenosides: crushing ginseng raw material into coarse powder, soaking in 50-70% ethanol solution, where the solid-liquid ratio is 1:10-1:20 (kg/l), conducting microwave extraction for 2-4 times, each time extracting 5-9 minutes, filtering the extract and allowing to stand, mixing the filtrates, and conducting vacuum distillation to recover ethanol under microwave condition to obtain crude extract of total ginsenoside; adding 5-10 times volume of water into the extract, heating at 70-80 degrees C in a microwave generator for 1-3 minutes, and filtering while hot, washing the filtrate with diethyl ether to remove the fat-soluble component, extracting with water-saturated n-butanol solution 2-3 times, conducting microwave vacuum distillation to recover concentrated n-butanol, and obtaining fine total ginsenosides; (ii) separating panaxadiol and panaxatriol total saponin: diluting the fine total ginsenosides with 10% ethanol solution to obtain diluent, where the ratio of extract to ethanol solution is 1:10-1:18 (kg/l), passing into macroporous adsorption resin column, adding 40% ethanol solution as eluent with flow rate of 3 ml/minute for analyzing, where the volume of ethanol is twice of diluent, and obtaining more than 25% panaxatriol saponin, and adding 80% ethanol solution into diluent for analyzing, where the volume of ethanol is twice of diluent, and obtaining more than 50% panaxadiol saponin eluate; (iii) degrading panaxadiol saponin: adding acetic acid into the eluate, where the volume fraction of acetic acid in the eluate is 1-5%, heating at 60-80 degrees C for 1.5-2 hours in a water bath, reacting, and passing via macroporous resin adsorption column, eluting acid ion and other water-soluble impurities with water, adding more than 80% ethanol solution for analysis, and conducting microwave vacuum distillation of eluate to obtain a mixture containing ginsenosides Rg3 and Rh2; and (iv) separating ginsenosides Rg3 and Rh2 monomer: adopting atmospheric pressure silica gel column separation for saponin mixture, using a mixture of chloroform and methanol as eluent, to respectively obtain Rg3 and Rh2, further dissolving Rg3 and Rh2 in methanol, to obtain dissolved solute, and re-crystallizing with water 2-3 times, where the content of pure Rg3 and Rh2 is more than 90%.