Following the expansion of a sequential operation substation， the newly added operation order sheets will likely involve the bay between runs. This paper puts forward a new solution by using the bay level control unit as the sequential operation server with the operation order decomposed for each bay. The storage and execution of a certain operation order will be the responsibility of the testing and control device of the bay. The operation of the cross bay is managed and executed by the relevant bay operation orders combined. This solution will minimize the influence on sequential operation after substation expansion.