The invention relates to a preparation method of a good clustered glass fiber impregnating agent and belongs to the technical field of impregnating agents. The preparation method comprises the following steps: extracting humic acid from peat as a matrix; by taking common rosin as a modifying raw material, carrying out an addition reaction with the humic acid to obtain a modified substance; grafting and compounding rosin and humic acid to form a cationic surface active agent; and adding the rosin to reduce the viscosity of an emulsion, wherein the penetrative speed of the impregnating agent toglass fibers is higher, the adhesive fore of the emulsion to the glass fibers is increased, and a continuous film structure is more easily formed; moreover, the transfer effect of stress and effect onthe glass fibers is improved by means of flexible chain structures in a silica gel, the spreadability of a film forming agent on the surfaces of the glass fibers is increased, the coating effect is more uniform, the surfaces of the glass fibers are modified well, and the clustering property of the glass fibers is improved effectively.