The eco-friendly phase-change gel drilling sealant is formulated from environmentally sustainable water-soluble polymers and is designed for sealing gas extraction boreholes in underground coal mines. It offers advantages such as excellent borehole sealing performance, minimal usage requirements, environmental degradability, controllable phase transition, and low cost. The material adapts to diverse sealing needs throughout the entire borehole sealing process, including low-resistance grouting, low-viscosity penetration, high-viscosity bonding, dynamic sealing, and green degradation. It increases the average methane extraction concentration per borehole by 1.2 to 1.5 times or more, maintaining it above 30% long-term, effectively ensuring high-quality gas extraction from the borehole. Simultaneously, the material's degradability enables recovery of in-hole extraction equipment, fundamentally reducing per-hole sealing costs. Its per-hole usage is only 3%–5% of cement-based materials, significantly lowering labor intensity for field personnel and providing reliable material support for the development of intelligent drill-while-sealing technology.