Abstract: Spiral tube separator is widely used in the separation of immiscible media in the fields of petroleum, chemical industry and environmental engineering because of its simple structure, economy and efficiency, but different mixed media have different requirements for centrifugal force in the spiral tube separation.at present, the spiral tube structure needs to continuously increase the inlet pressure for medium separation with small density difference, in order to obtain higher centrifugal force but also increase the energy consumption of treatment.How to enhance the universality of the spiral tube to the pre-separation medium through structural improvement, so as to further improve the oil-water separation accuracy of the spiral tube separator is particularly important to effectively reduce the oil-water separation cost and simplify the treatment process.In order to further improve the oil-water separation accuracy of the current spiral tube oil-water separator and change the pitch distribution of the spiral tube, this paper puts forward a structure of the variable distance spiral tube oil-water separator, and uses the method of orthogonal test and computational fluid dynamics (CFD) to optimize the main structural parameters of the variable distance spiral tube oil-water separator, and carries on the visual analysis and variance analysis to the orthogonal test results.The optimum ratio of structural parameters is obtained, and the optimum cone angle of spiral tube is 5°, the optimum number of spiral tube is 7, and the optimum diameter of overflow pipe is 70 mm.The oil-water separation efficiency of the optimized structure is improved from 49.4% of the initial structure to 57.34%.The structure of variable distance spiral tube before and after optimization is numerically simulated and analyzed, and the separation efficiency of the two structures is obtained under the condition of different inlet flow rate and different shunt ratio.The results show that within the range of 2-5 m³/h, the shunt ratio is in the range of 5%-35%, and the oil-water separation efficiency increases obviously with the increase of inlet flow.After optimization, the optimum split ratio of spiral separator is 20%.The oil-water separation efficiency of the optimized spiral separator structure has been significantly improved.