Flare system is a safety measure for the emergency shutdown of ethylene plant, and its design is very important. Adopting necessary emission reduction measures is helpful to reduce the total load of flare system. This paper introduces the emission reduction measures adopted in ethylene plant, and analyzes the principle of flare control, the setting of pressure control valve, the emission reduction of flare gas in compressor system, the emission reduction of flare in distillation tower system, and the design and calculation basis of flare system. By taking certain emission reduction measures, the investment of ethylene plant can be further reduced on the premise of ensuring safety, thus improving its market competitiveness.