Preparation method of acid-alkali-resistant wetting agent

The invention discloses a preparation method of an acid-alkali-resistant wetting agent.The preparation method particularly comprises the steps that 0-15 parts by mass of maleic anhydride, 0-15 parts by mass of dodecyl polyoxyethylene ether, 0-15 parts by mass of nonylphenol polyoxyethylene ether and 0-5 parts by mass of p-toluenesulfonic acid are added into a reaction kettle, the vacuum degree is controlled within the range of 0.095 MPa-0.1 MPa at the temperature of 120 DEG C-220 DEG C, reacting is performed for 2-10 h, an acid value and a hydroxyl value of reaction liquid are measured, and if the acid value and the hydroxyl value do not reach the standard, reacting is continuously performed until the acid value and the hydroxyl value both reach the standard; if the acid value and the hydroxyl value reach the standard, the temperature of the reaction liquid is lowered to 80 DEG C-90 DEG C, 0-8 parts of by mass of sodium hydrogen sulfite and 0-5 parts by mass of sodium acetate are added, stirring is performed