The invention discloses a method for detecting non-metallic inclusions in steel, which adopts the following process: carrying out 
solid solution strengthening on a sample to be detected to prepare a rod-shaped sample; taking a stainless steel sleeve as a 
cathode, taking a rod-shaped sample as an 
anode, and performing electrolytic extraction by adopting a 
semipermeable membrane for isolation, wherein the 
electrolyte comprises the following components in proportion: 0.01 g / ml-0. 1 g / ml of 
tetramethylammonium chloride, 0.1 ml / ml-0. 25 ml / ml of 
acetylacetone and the balance of a 
methanol solution with the 
mass fraction of 95%-99%; dissolving the electrolyzed 
electrolyte in absolute ethyl 
alcohol, and filtering by using a filter membrane; dissolving the inclusions on the filter membrane in the absolute ethyl 
alcohol solution again, and obtaining clean inclusions after 
magnetic separation and filtering; inlaying clean inclusions on a 
metal plane with a conductive 
adhesive, and spraying 
platinum to prepare an ASPEX observation sample; and detecting the ASPEX observation sample by using an ASPEX automatic 
scanning electron microscope to obtain detection information of all extracted inclusions. According to the method, the non-metallic inclusions in the steel can be nondestructively, completely and quickly detected, and the manual 
workload and errors caused by manual work are greatly reduced.