The invention discloses a high-efficient 
biomass charcoal coated 
fertilizer and a preparation method thereof. The 
fertilizer is prepared from the following raw materials by weight: 20 to 35 parts of walnut shells, 8 to 15 parts of 
bagasse, 12 to 20 parts of moso bamboo, 20 to 26 parts of 
urea, 80 to 100 parts of a diluted 
hydrochloric acid solution with a concentration of 1 mol / L, 10 to 15 parts of 
ammonium humate, 20 to 30 parts of 
potassium sulfate, 5 to 10 parts of 
ferrous sulfate, 18 to 25 parts of 
calcium monohydrogen 
phosphate, 6 to 10 parts of clay, 6 to 10 parts of 
zinc chloride, 4 to 5 parts of a binder and a proper amount of water. According to the invention, the walnut shells containing rich 
lignin, the 
bagasse and the like are ground into particles with appropriate sizes, and are subjected to high-temperature sealed 
carbonization so as to obtain a porous 
activated carbon component, and the porous 
activated carbon component is combined with 
polyvinyl alcohol so as to prepare a 
fertilizer controlled-release 
coating agent which has excellent controlled-release effect; meanwhile, the obtained 
granular activated carbon component has the advantages of large sizes, intensive pores, tight structure, insusceptible breakage, durability in use, and higher 
cost performance; besides, through timely washing with 
hydrochloric acid, the pores are timely dredged, and more obvious effects are achieved.