A system for coupling geothermal energy storage with coalbed methane extraction in an unmineable coalbed includes a ground heat collection unit, a heat injection and energy storage unit, and a cogeneration unit. The ground heat collection unit is configured to collect and convert solar energy and surplus electricity from wind and photovoltaic power generation into high-temperature thermal energy. The heat injection and energy storage unit includes a heat injection device, an injection well, an extraction well, an artificial heat storage space, an upper covering stratum, and a lower covering stratum. The cogeneration unit is connected to the extraction well and configured to utilize the high-temperature thermal energy for heating/cooling and recycle the free coalbed methane for gas supply and power generation. In this way, unmineable coalbed resources are developed, and the solar energy and the surplus electricity from wind and photovoltaic power generation are absorbed.