put 1 mol trioctylphenol into the reaction kettle, reinforce the alkali as the catalyst, and the amount of solid alkali added is equivalent to about 0.3% of trioctylphenol. after heating and melting, nitrogen is used to replace the air in the kettle, and the air in the kettle is driven by air. Then ethylene oxide is introduced at a condensation temperature of 130~150 ℃ and a pressure of 0.2 MPa. When the ratio of ethylene oxide is 4 mol, the cloud point of 1% aqueous solution is measured by sampling, and the cloud point of 1% aqueous solution is 50~70 ℃. After condensation, a regulator is added for compounding, and then glacial acetic acid is used to neutralize to a pH value of about 7.5. Cooling, discharging and filling the finished product.