The invention discloses a sewage treatment agent special for printing and dyeing wastewater. The sewage treatment agent is prepared from, by weight, coal ash, wooden activated carbon, poly aluminium chloride, polyferric sulfate, polyacrylamide, ammonium persulfate, sodium carbonate, poly-ferric aluminum sulfate, aluminum sulfate, yttrium oxalate, manganese sulfate, sodium bentonite, zeolite, sepiolite, modified lignin sulfonate, alkylphenol ethoxylates, amino trimethylene phosphonic acid, menthone, thiourea, cationoid starch derivatives, sodium dodecyl benzene sulfonate, dimethyl diallyl ammonium chloride, octaphenyl polyoxyethyiene, glycerin monostearate, peroxiredoxin and microbial bacterial liquid. The microbial bacterial liquid is prepared from saccharomycetes, fusarium oxysporum, proteusbacillus vulgaris, neurospora and mycoplana. The invention further provides a preparation method of the sewage treatment agent. The prepared sewage treatment agent is good in treatment effect on the printing and dyeing wastewater, the preparation method is simple, and no secondary pollution exists.