The invention discloses a method for recovering heavy metal mercury from an adsorbent. Compressed air carrying the adsorbent enters a plasma reactor. Plasma in the plasma furnace can generate the hightemperature of 10000 DEG C, the temperature in the furnace can be changed by controlling the input power, and zero-valent mercury, monovalent mercury and divalent mercury which are physically adsorbed and chemically adsorbed in the adsorbent are released again at the high temperature in the plasma furnace; meanwhile, a lot of high-energy electrons and ions are generated under plasma discharge, and the high-energy electrons and ions can erode the surface of the adsorbent, so that the adsorbed mercury is easier to desorb; and in an air atmosphere, the plasma can generate ozone and oxygen atomswith extremely strong oxidability, and the ozone and the oxygen atoms are introduced into the aqueous solution together with gaseous mercury. Divalent mercury can be directly dissolved in the aqueoussolution, and ozone and oxygen atoms with extremely high oxidability can oxidize released elemental mercury and monovalent mercury into divalent mercury which is absorbed by the aqueous solution. After treatment, mercury in the adsorbent is absorbed by the solution, and can be used for industrial application.