The present invention discloses a system and a method for front-end hydrogenation impurity-removal purifying recovery of a catalytic dry gas. The system comprises a compressor, a reactor, a cooler, an absorption tower and a desorption tower; the compressor has two or more sections, the reactor is arranged between the compressor sections; the last compressor section is in sequence connected with the cooler and the absorption tower; the bottom of the absorption tower is connected with the desorption tower, and the desorption tower is connected with the upper part of the absorption tower. The method is as follows: in a section for pressure rise of the catalytic dry gas, deoxygenation purification of the catalytic dry gas is performed, and a concentrated C 2 fraction can be obtained by absorption and desorption. The system is less in apparatus, low in energy consumption, simple in process, and high in recovery rate.