The pre-processes of the hydrogen production unit and the methanol unit of a certain company are highly consistent, and the process parameters are similar. Due to the shutdown of reformer in the hydrogen production unit, in order to meet the hydrogen demand for startup after maintenance, high-temperature conversion gas produced by the methanol unit was used as the feed gas for medium-temperature shift reaction in the hydrogen production unit. Through process optimization and the co-production and co-adjustment strategy, the conversion process of methanol unit was closely connected with the process flow of hydrogen production unit including medium-temperature shift, compressor, medium-temperature shift system and feedstock preheating furnace, so as to meet the hydrogen demand for start-up of production units. At the same time, the start-up time of the hydrogen production unit could be reduced from 5 days to 36 hours, greatly improving the emergency hydrogen production capacity of the unit. When the ethylene unit was in operation and the total amount of crude hydrogen and wet hydrogen was 580 kg/h, the optimized process of the new methanol unit and hydrogen production unit could meet the maximum external hydrogen supply of 12,506 m³/h. Through process optimization and co-production and co-adjustment, the operation bottleneck of the hydrogen production unit was eliminated. At the same time, the mutual backup of hydrogen production unit was achieved, the task of guaranteeing hydrogen supply during startup was completed, and the dual goals of technical research and quality improvement with efficiency enhancement were achieved.