The present invention belongs to the technical field of gas separation, in particular to a pressure swing adsorption decarbonization device and process that can improve processing load and recovery and achieve energy saving; the pressure swing adsorption decarbonization device includes a water separator that is communicated to the raw gas pipelines; the water separator is respectively communicated with an air inlet of a first section adsorption tower group through pipelines, and an air outlet of the first section adsorption tower group is communicated with the air inlet of a second section adsorption tower group through a semi-finished buffer tank, and the air outlet of the second section adsorption tower group sequentially communicate with the purified gas buffer tank and the high-pressure machine through pipelines; the device can increase processing load and recovery, and achieve energy saving.