The invention discloses a dyeing and printing auxiliary agent, and relates to the technical field of weaving dyeing and printing. The dyeing and printing auxiliary agent is prepared from the followingraw materials in parts by weight: 10 to 15 parts of guar gum, 7 to 9.5 parts of polyalkyl acrylate, 15 to 20 parts of sodium carboxymethyl cellulose, 5 to 8 parts of stearyldimethylbenzylammonium chloride, 2 to 3 parts of tannin and 10 to 15 parts of barium chloride. A preparation method comprises the following steps of weighing raw materials according to the weight parts; adding the polyalkyl acrylate, the sodium carboxymethyl cellulose and the stearyldimethylbenzylammonium chloride into a reaction kettle; performing temperature rise and stirring to complete reaction; performing cooling; adding the tannin and the barium chloride; performing stirring and temperature rise; adding the guar gum; performing uniform stirring. The dyeing and printing auxiliary agent has the advantages that thecolor fastness is high; the color protection performance is good; the color fading prevention effect is achieved.