With the continuous improvement of national environmental protection standards, enterprises achieve the emission reduction and up-to-standard discharge of the three wastes by optimizing the start-up and shutdown scheme and effectively balancing the startup and shutdown schedule. For ethylene plant with complex process flow, it is especially important to achieve environmental-friendly, economical and high-efficiency startup and shutdown. Following the principle of environmental protection priority, the ethylene plant of Shanghai SECCO strictly controls the discharge of the three wastes during startup and shutdown, takes economy and high-efficiency as the goal, maximizes the recovery of hydrocarbons, and balances the environmental protection and economy during startup and shutdown by means of schedule control. Good results have been achieved.