The invention provides a chicken manure organic fertilizer and a preparation method thereof, and relates to the technical field of fertilizers. The chicken manure organic fertilizer is mainly prepared from, by mass, 30-40 parts of chicken manure, 10-20 parts of wheat bran, 10-20 parts of zeolite powder, 10-20 parts of needle mushroom residues, 5-10 parts of tobacco powder, 5-10 parts of sugar cane pomace, 1-5 parts of silkworm excrement and 1-5 parts of a composite microbial agent, the composite microbial agent is a mixture containing Aspergillus oryzae, Bacillus subtilis, yeast, actinomycetes, ammonifying bacteria and photosynthetic bacteria according to a mass ratio of (1-3):(1-3):(1-3):(1-3 ):(1-3):(1-3). The chicken manure organic fertilizer alleviates the technical problem of crop insect diseases brought by the direct application of existing chicken manure to the field, reaches the harmlessness of parasites, eggs and pathogens existing in the chicken manure, increases the crop yield, can kill and repel pests, makes crops green and safe, and eliminates people's hidden health troubles.