Method for analyzing mixed acid concentration of silicon etching solution

The invention discloses a method for analyzing the mixed acid concentration of a silicon etching solution. The method comprises the steps of taking a mixed acid sample of nitric acid, hydrofluoric acid and acetic acid to be detected, respectively adding an aprotic organic solvent and an anti-precipitation interference solvent into the mixed acid sample to prepare a silicon etching mixed acid solution, and dropwise adding a calibrated strong alkali aqueous solution into the silicon etching mixed acid solution through an automatic potentiometric titrator until a first jump part, a second jump part and a third jump part respectively appear; and calculating the concentration of the silicon etching liquid mixed acid, namely nitric acid, hydrofluoric acid and acetic acid, according to the volumeof the strong alkali aqueous solution consumed by the midpoints of the first, second and third jump parts. The concentrations of nitric acid, hydrofluoric acid and acetic acid contained in the silicon etching solution are easily, quickly and accurately measured by a one-step method, automatic dropwise adding and automatic calculation of the titration result are realized; the method is efficient and quick, the precision is improved, and time and labor are saved.