To clarify the effects of chemical demulsifiers, temperature, and polymers on the deformation and coalescence behaviors of dispersed droplets in water-in-oil emulsions under high-frequency/high-voltage pulsed alternating current (AC) electric field, microscopic high-speed photography was employed to systematically analyze the mechanisms of droplet movement influenced by different factors. The results showed that under the electric field alone, the degree of droplet deformation increased with the increase of electric field strength, and the critical electric field strength for droplet breakup was 5.0 kV/cm; the optimal electric field parameters for the coalescence of two droplets were 3.0 kV/cm and 2.5 kHz. Increasing temperature could enhance droplet deformation, reduce its critical electric field strength for breakup, and shorten the contact time between the two droplets. However, excessively high temperature was not conducive to droplet coalescence. When the electric field was used synergistically with a demulsifier, there was an optimal demulsifier concentration of 100 mg/L. The shortest contact time between the two droplets was 6 ms when the electric field strength was 3.0 kV/cm. The presence of polymer would inhibited droplet deformation and increased the electric field strength required for coalescence. However, the addition of a demulsifier and an increase in temperature could effectively promote coalescence and improve demulsification efficiency. The findings of this study can provide theoretical support and practical guidance for determining operating parameters of high-efficiency demulsification and dehydration equipment for the treatment of polymer flooding production fluid.