The invention relates to a 
biocide for pipeline cleaning, and a preparation method thereof, wherein the 
biocide comprises the following raw materials by weight: 20-30 parts of 2,2'-dihydroxy-5,5'-dichlorophenylmethane, 10-20 parts of 2,2-dibromo-3-carbamoylacetonitrile, 5-10 parts of 
zinc dialkyl dithiophosphate, 5-10 parts of 
methylene bisstearamide, 1-3 parts of 3,7-dimethyl-2,6-octadiene 
nitrile, 10-15 parts of 
boric acid diglyceride sodium monostearate, and 200-300 parts of deionized water. According to the present invention, the 
biocide can form the protection film on the 
metal surface, such that the 
catalytic oxidation effect of the 
metal can be eliminated, and the 
surface corrosion and the surface wear on the 
metal can be prevented; the biocide can reduce the friction between the 
polymer molecular chains, can improve the 
lubricity among various raw materials, can reduce the reaction time, and can improve the sterilization and 
algae-killing effect; and the biocide has the mild 
odor, can make the treated pipeline maintain the lemon 
aroma, can 
label the treated pipeline in the 
odor manner so as to avoid the 
multiple treatments within a short time, and can improve the 
management efficiency and reduce the use cost.