The invention discloses a spinning water-based treating agent and a preparation method thereof. The preparation method comprises the following steps: weighting pure water, polyvinyl alcohol, crylic acid, ammonium persulfate, medium chrome yellow, monoisopropanolamine, methacrylic acid, concentrated hydrochloric acid, n-butyl aldehyde ketone, dihydroxy diphenyl ether and essence, stirring the raw materials and then grinding. The spinning water-based treating agent is applied to spinning surface protection, the surface decorative effect is good and the viscosity is 20-30 Pa.S; the phenomena of spot and shrinkage cavity can be prevented and the butyral degree is 8-12%; the leveling property and pigment wettability are excellent; the peel strength is 5-7 MN/cm; the antibacterial property and mildew resistance of the spinning articles are greatly increased; the elongation is 120-160%.