A cold hydrogen distribution pipe for a hydrogenation reactor comprises a feeding pipe connected with a cold hydrogen storage tank, a plurality of distribution branch pipes are arranged on the feeding pipe, and evenly-distributed columnar nozzles are arranged at the bottom of the feeding pipe and the bottoms of the distribution branch pipes. The cold hydrogen distribution pipe has the advantages of being reliable in structure and sufficient in mixing of hydrogen and reactant flow; branch type or annular design is adopted so that cold hydrogen can flow in the branch or circumferential direction and flow out of the nozzles at the bottoms of the distribution branch pipes. The cold hydrogen distribution pipe can well suppress material temperature drop nonuniformity caused by nonuniform distribution of cold hydrogen and prevent catalyst failures caused by local hot points, and has very good economic benefits and social benefits.