The invention discloses a multifunctional environmentally-friendly universal spinning sizing agent which is prepared from, by weight, 3-9 parts of chitosan, 15-20 parts of acetate starch, 1-3 parts of carboxymethylcellulose, 0.5-1 part of bentonite, 2-3 parts of sodium silicate, 5-10 parts of itaconic acid, 5-15 parts of acrylamide, 4-8 parts of butyl acrylate, 2-6 parts of butyl acrylate, 1-1.5 parts of initiator, 0.8-1.5 parts of a catalyst, 2-5 parts of calcium chloride and 5-10 parts of deionized water. The invention discloses a preparation method of the spinning sizing agent, viscosity of the spinning sizing agent is stable, excellent chemical stability and thermal stability are achieved, sizing and desizing are conducted easily, slurry wastewater is easy to process, the size film property and the sizing property are good, moisture absorption and stickiness viscidity are low, the multifunctional environmentally-friendly universal spinning sizing agent is environmentally friendly, and environmental pollution is reduced.