Halogen-containing solid wastes have become a global challenge due to their complex composition and potential environmental hazards. Molten salt technology (MST), as an efficient thermal treatment method, utilizes high-temperature molten salts as the reaction medium to effectively degrade organic compounds, capture hydrogen halides, and suppress dioxin formation, while simultaneously enabling metal recovery and carbon reduction. This paper systematically reviews the latest advances in molten salt technology for the treatment of halogen-containing solid wastes, including the reaction characteristics, thermodynamic mechanisms, and applicability of alkaline, carbonate, nitrate, and composite molten salt systems. Through a multi-criteria analysis framework, the advantages and disadvantages of different molten salt systems are compared, and optimized technical routes are proposed for mixed waste streams. The study reveals that the Li₂CO₃-Na₂CO₃-K₂CO₃ ternary carbonate system exhibits excellent performance in organic destruction and removal efficiency and halogen capture, while the NaOH-KOH low-melting-point system offers advantages in energy consumption and equipment simplicity. The innovation of this work lies in the first proposal of a “multi-criteria comparison framework” and the identification of future research priorities. This study provides academic insights and technical guidance for green hazardous waste management and promotes the transition toward a circular economy.