The invention relates to an 
active carbon preparing method by adopting walnut shell as 
raw material and an application of the 
active carbon. The walnut shell is adopted as the 
raw material. The 
active carbon is prepared by adoption of a vacuum 
pyrolysis method through steps of smashing, 
drying, 
charring, puffing for activation, cooling, discharging, sieving, and the like. The obtained active carbon is applied as a microbial 
fertilizer carrier. The preparing method and the application are advantaged by: short production period, low 
reaction temperature, low production cost, low 
energy consumption, no 
pollution to the environment, and capability of improving the soil granular structure, reducing soil hardening, enhancing the 
water retention property of the soil, playing a role of 
nitrogen-fixation 
controlled release fertilizers, and reducing the using amount of fertilizers and decomposed 
crop straw when the active carbon is applied as a microbial 
fertilizer carrier and used in the 
agriculture.