The invention aims to propose a humidity adjusting device, with small size and capable of adjusting air humidity, of a base station and a humidity adjusting method thereof. The humidity adjusting device of the base station comprises an indoor air channel, a regenerated air channel, an absorbing turntable, a regenerated air heating part and a rotating wheel frame provided with a motor; and the rotating wheel frame is used for supporting and driving the absorbing turntable, and is formed with a first opening part for passing through indoor air and a second opening part for passing through regenerated air, so that the indoor air and the regenerated air both can penetrate through the absorbing turntable. The humidity adjusting device of the base station is characterized in that a water storage pool is arranged below the absorbing turntable; the rotating wheel frame is mounted on a lifting bracket; and the absorbing turntable can leave from the water surface of the water storage pool when the lifting bracket is hoisted, and is partially leached in water of the water storage pool when the lifting bracket is descended. The humidity adjusting device of the base station organically combines a humidifying function with a dehumidifying function, and is simple in structure, small in size and convenient for control.