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To obtain the great surface quality of Ti–6Al–4V and achieve high efficiency in the polishing process, the chemistry enhanced shear thickening polishing (C-STP) was proposed, and the polishing performance of different pH slurry was studied. The results show that the material removal rate gradually increases as the pH value decreases from 10 to 1, and the best surface quality is obtained at pH 2. The corrosion current density and potential were measured by potentiodynamic polarization under three typical pH values. It is confirmed that the most massive corrosion rate presents at pH 2, and the passive film is most susceptible to be produced at pH 10. The reaction resistance was measured by electrochemical impedance spectroscopy to clarify the polishing mechanism. Under acidic conditions, the chemical reaction product on the surface can be quickly removed by mechanical action of the abrasive. On the contrary, the passive film formed on the surface under the alkaline condition is difficult to be removed. The corrosion reaction products were determined by X-ray photoelectron, and the chemical reaction under acid-base environment was derived. MRR reached 107.3 nm/min under the selected process parameters, and the surface roughness (S a) is reduced from 124 nm to 8.6 nm within 15 min. • A new method Chemistry enhanced Shear Thickening Polishing (C-STP) is proposed to polish Ti–6Al–4V efficiently, and the influence of pH value of slurry on Ti–6Al–4V polishing performance is investigated. • MRR gradually increases from 26.1 nm/min to 115.4 nm/min as the pH value decreases. The best surface roughness (Sa) is 8.6 nm obtained at pH 2 and the removal rate reaches the 107.3 nm/min. • Under alkaline conditions, the passive film on the surface of Ti–6Al–4V is produced and difficult to be removed, result in low removal efficiency and surface quality. Under acidic conditions, a corrosion layer is produced which can be quickly removed by abrasive particles. [ABSTRACT FROM AUTHOR]