The invention belongs to underground energy resource development reservoir transformation. A mining principle is environment friendliness and low-pressure super-cold liquefaction combined mining technology. Combustible ice can be liquefied into a super-cold fluid, namely free methane, by adopting a well network super-cold liquefaction technology; meanwhile, the overall low pressure of a combustible ice reservoir is realized by reducing the pressure in a combined manner of reducing the pressure of a slit by enlarging a nano-slit by a well network, reducing the pressure close to the bottom of a well by single well pumping and discharging, and wholly reducing the pressure of a well control area by superposing pressure drops of multiple wells; the speed of liquefying the combustible ice into the free methane of the overall development area is improved quickly and effectively by comprehensively taking the measures of carbon dioxide hydrate or nitrogen hydrate replacement, geothermal heating and the like. Multi-period less huff and quick puff is realized; the free methane only flows in a combustible ice stratum, a well shaft pipe and a gathering and transportation pipe network; authigenic carbon dioxide hydrate and nitrogen hydrate replace the gaps of the free methane; the three measures ensure that combustible ice industrial mining is controlled safely and environmentally friendly; blowout accidents are prevented, and disasters, such as tsunami, submarine landslide and seawater poisoning are prevented.