The invention provides a method for preparing industrial-grade phosphoric acid by an emulsification, extraction and purification wet method. The method comprises the sequential process steps of primary de-coloring, emulsification and extraction, emulsification and washing, emulsification and reverse extraction, concentration, dearsenification and heavy metal removing, secondary deep de-coloring and concentration adjustment. A method for food-grade phosphoric acid by the emulsification, extraction and purification wet method comprises the sequential process steps of primary de-coloring, emulsification and extraction, emulsification and washing, emulsification and reverse extraction, concentration, dearsenification and heavy metal removing, secondary deep de-coloring, defluorination and concentration adjustment. The emulsification and extraction step comprises the following steps of: agitating at normal pressure and at a temperature of 50-60 DEG C for 10-60 seconds at the speed of 500-3000 r/min; and agitating at the normal pressure and at the temperature of 50-60 DEG C for 60-240 seconds at the speed of 120-220 r/min; the emulsification and washing step comprises the following steps of: agitating at the normal pressure and at the temperature of 50-60 DEG C for 10-60 seconds at the speed of 500-3000 r/min; and agitating at the normal pressure and at the temperature of 50-60 DEG C for 60-240 seconds at the speed of 120-220 r/min; and the emulsification and reverse extraction step comprises the following steps of: agitating at the normal pressure and at the temperature of 50-60 DEG C for 10-60 seconds at the speed of 500-3000 r/min; and agitating at the normal pressure and at the temperature of 50-60 DEG C for 60-240 seconds at the speed of 120-220 r/min.