The utility model discloses an experimental device for heterogeneous attitude CO2 adsorbs desorption to big rock specimen, including air supply supply system, vacuum pumping system, constant voltage equipment, heating device, set up the sample room in heating device, manual measuring pump and monitored control system, the air supply supply system includes CO2 gas cylinder and liquid CO2 bottle, CO2 gas cylinder, liquid CO2 bottle, vacuum pumping system are connected to a house steward through the cross valve incorporation, and this house steward passes through constant voltage equipment and is connected with the sample room, manual measuring pump is connected with the sample room for apply confined pressure and axle load for the sample in the sample room, be provided with a plurality of sensors in the sample room, a plurality of sensors are connected with monitored control system, the experimental apparatus still includes buffer and gaseous supercharging device, gaseous supercharging device is connected with the buffer, the buffer is connected between liquid CO2 bottle and cross valve. The utility model discloses can study the absorption desorption process of heterogeneous attitude CO2 to big rock specimen to the CO2 that can study different phases adsorbs the law that influences of desorption to big rock specimen.