Abstract: Under the power operating state of the PWR nuclear power unit,hydrogen cover is always being maintained in the reactor coolant system.However, during the shutdown oxidation of the unit,the reactor needs to be opened.In order to avoid the explosion of hydrogen and oxygen mixture,it is necessary to remove the hydrogen first and reduce the dissolved hydrogen content of the primary circuit below the specification value to carry out the oxidation operation.In the process of PWR nuclear power plant shutdown oxidation,the effective control of dissolved hydrogen in the primary circuit can determine whether or not the chemical control process will become the key path for outage.This article combines the practice of controlling the dissolved hydrogen in the primary circuit oxi dation process of the No.1-4 M310 units that have been commercialized by Fuqing Nuclear Power.Starting from the requirements and basic principles of the dissolved hydrogen chemical control of the reactor coolant system,the possibility of the shutdown oxidation process summarize and study the emergence of dissolved hydrogen related issues, and propose optimized and improved strategies for dissolved hydrogen chemical control to guide the unit to respond,and ultimately achieve the goals of improving nuclear safety,shortening the overhaul period,and increasing the economic benefits of refueling overhaul.