The effect of high-density electroshocking on the solid phase transformation of Ti-6.6Al-3.4Mo alloy was studied in this paper. The microstructure at the same position of the specimens before and after electroshocking treatment with different parameters was characterized by the optical microscopy and scanning electron microscopy. The experimental results reveal that the refined and spheroidized primary alpha phase can be obtained under the appropriate treatment condition. Meanwhile, the fine orthorhombic alpha'' phase at submicron was discovered by the X-ray diffraction and transmission electron microscopy in the transformation products. A physical model was established to analyze non-uniform current distribution at microscale and to explain the spheroidization mechanism. The phase transition process was interpreted from the point of view of thermodynamics.