Abstract: The alcohol hydrocarbon separator in the offshore ethylene glycol regeneration desalination unit is large in size and low in separation efficiency, which leads to the increase of separator barrel and investment. In this paper, the coalescence separation section of ethylene glycol rich liquid and condensate is optimized to improve the coalescence separation efficiency and reduce the size of the device. Firstly, the Fluent software is used to analyze the influence of the spacing, wavelength, amplitude and inclination of corrugated coalescing plates on their separation efficiency under different flow velocities. Then the Box Behnken Design (BBD) in response surface method is used to design the test scheme and establish the response model between the separation efficiency of coalescing plates and various influencing parameters. The results show that the concentration of oil phase at the outlet of the coalescer plate is proportionate to the increase of the distance between the coalescer plates; The separation efficiency also increases with the increase of wavelength and amplitude. Besides, with the increase of inclination, the separation efficiency first increases and then decreases. Based on this, the genetic algorithm is utilized to optimize the coalescence separation section to improve the separation efficiency per unit volume, which reduces the coalescence section volume by 19.06%, and effectively reduces the size of the alcohol hydrocarbon separator.