Reconfigurable coding metasurfaces have demonstrated promising potential in biomedical detection and imaging applications due to their flexible control capabilities and rapid response to electromagnetic stimuli. However, it is difficult to realize reconfiguration in the terahertz band with metasurfaces based on semiconductor components. Meanwhile, metasurfaces based on tunable materials often struggle to simultaneously attain high transmission efficiency and a wide phase tuning range. Herein, a transmissive metasurface unit cell based on vanadium dioxide (VO₂) is proposed, which achieves a phase difference of 180° at 0.1 THz while maintaining a high transmittance of 67%. The analysis based on an equivalent circuit model reveals the mechanism underlying the transition of resonant modes in the unit cell before and after the phase change of VO₂, and explains the principle of its phase broadening. Then a genetic algorithm is used to optimize the array arrangement of the metasurface, and the phase state of the unit cell is dynamically adjusted by the column-by-column electric control method, which successfully enables the transmitted beam deflection in the range of −45° to 45°.