The application prospects of titanium alloy in the manufacturing of microcomponents in aerospace, biomedical, and precision instruments are promising. The jet electrochemical micromilling (JEMM) technology, based on the principle of electrochemical anodic dissolution to remove material, holds advantages in the micromachining of titanium alloys. However, a dense passive film is easily formed on the surface of titanium alloys under the influence of electrochemical processes, making the material dissolution process difficult to sustain stably. To overcome this problem, the polarization curves of Ti–6Al–4V were measured in electrolytes with different compositions and concentrations. It was found that a 10% NaCl (mass fraction) solution exhibited a strong capability in breaking the passive film, and the passivation and dissolution process were relatively stable. Building upon this, the effect of the inner diameter of the metal nozzle, machining voltage, and scanning speed on the aspect ratio of microgrooves and the range of stray corrosion in JEMM was investigated. Finally, a square spiral microstructure was fabricated on the Ti–6Al–4V surface using optimal parameters with a metal nozzle inner diameter of 300 μm, machining voltage of 35 V, and scanning speed of 75 μm/s. The resulting groove had an average width of 823.1 μm (standard deviation of 10.42 μm), an average depth of 157.26 μm (standard deviation of 5.89 μm), and a surface roughness of 2.006 μm (standard deviation of 0.088 μm).