UE extraction and GC-MS determination are used to analyze organic ingredients adhesion to particles in GAC effluents, and examine the types, characteristics, sources, transformation mechanisms and distribution of organic matter attached to particles. The results indicate that the weak polar organic adhesion to particles in GAC effluents mainly included the hydrocarbons(37.75%), esters and ketone (32.60%). There is a slightly different amount of organic matter attached to particles with different sizes. The transfer and transformation of organic matter attached to particles present the changes of number and type of functional group, and molecular structure determined the migration and transformation behavior of physical and chemical properties of organisms in the environment, and the internal eco-toxicological effects. And on this basis, it is necessary to control the number of effluent particles to reduce THMs and improve chemical security.