The invention discloses a chemical abrasive flow polishing method for 3D printed titanium alloy. The method comprises the following steps that (1) the titanium alloy is ultrasonically cleaned; (2) purified water, methanol, n-butanol, hydrofluoric acid and nitric acid are sequentially weighed with volume ratio being 100:(2-4):(2-4):(5-7):(15-21) and mixed, a polishing solution is obtained, and thenalpha-Al2O3 particles are added into the polishing solution with the solid-liquid mass ratio being 1 g to 80 ml, the solution is stirred for intensive mixing and cooled, stirring is stopped after thesolution is cooled to room temperature, and an abrasive polishing solution is obtained; (3) a 3D printed titanium alloy sample is immersed in the abrasive polishing solution, the abrasive polishing solution flows with the flow rate being 600 L/h for circulating abrasive flow polishing on the surface of the 3D printed titanium alloy sample, and the abrasive polishing time is 3 to 5 hours; and (4)the 3D printed titanium alloy sample is taken out and ultrasonically cleaned, and the 3D printed titanium alloy is obtained. The roughness of the 3D printed titanium alloy obtained through the methodis significantly reduced, and the brightness of the 3D printed titanium alloy is improved significantly.