The invention provides a preparation and energy recycling system of coal-bed gas hydrate. The preparation and energy recycling system comprises a coal-bed gas booster pump, a refrigerant heat exchanger, a tail gas cooling capacity recycler, an un-reacted coal-bed gas cooling capacity recycler, a hydrate reactor, a hydrate decomposer, a saturated absorption liquid cooling capacity recycler, an absorption liquid circulating pump, and the like. A coal-bed gas is pressurized, cooled by saline water and liquid nitrogen through multiple steps; the coal-bed gas is ventilated from the bottom of the reactor to carry out countercurrent contact reaction with the adsorption liquid sprayed from the top of the reactor; saturated methane adsorption slurry is pumped into the decomposer by a discharging pump from the lower part of the reactor; the saturated absorption slurry carries out countercurrent indirect heat exchange with the absorption liquid entering the decomposer, and is re-pumped into the hydrate reactor after being cooled by the saline water; and methane discharged by the hydrate decomposer through a vent valve enters an LNG (liquefied natural gas) production system. Production cost of extracting methane from the coal-bed gas hydrate is greatly lowered by recycling the cooling capacity in the tail gas exhaustion gas, the cooling capacity in the un-reacted coal-bed gas, and cooling capacity in the statured absorption liquid.