put phenol 1 mol C8 ~ 10 olefin 1.75 mol into alkylation reactor, stir and raise the temperature to 140 ℃ to reflux, keep the temperature for 8 h, then cool and press into distillation reactor, and evaporate excess C8 ~ 10 olefin under reduced pressure. The residual alkylphenol is fed into the condensation kettle and 0.3% sodium hydroxide equivalent to the amount of phenol is added. Replace the air in the kettle with nitrogen, and after the air is removed, 4 mol of ethylene oxide is passed. The reaction temperature is maintained at (150±10)℃ and the pressure is 0.2~0.3 MPa. After passing ethylene oxide, the HLB value is measured by sampling, and the HLB value is 8.8 to the end of the reaction. The feed liquid is pumped into the neutralization kettle, neutralized with acetic acid to a pH value of 5.0~7.0, and the finished product is packaged by cooling and discharging.