In this paper, the ethylene products of an ethylene plant are studied. The large fluctuations in the CO content of cracking gas in a short period of time led to bed temperature runaways in C₂ hydrogenation reactor, and the pulverization and carbonization of catalysts led to a decrease in the activity of catalysts, resulting in high acetylene at the reactor outlet and low qualified rate of ethylene products. The temperature runaway in C₂ hydrogenation reactor caused by CO fluctuations under typical working conditions was analyzed, and strategies were formulated from two aspects of process adjustment and catalyst replacement, so as to effectively solve the problem.