Abstract: Ling’Ao Phase II Nuclear Power Plant is the first 1,000MW power project in China using domestic design methodology.Considering the operation and maintenance conditions,unequal column clearance is avoided as far as possible for main building design of Ling’ao Nuclear Power Station Phase II Conventional Island to satisfy the requirements on the module by civil construction.Since the external dimensions of turbine generator and condenser and the subsection length of deaerator of Ling’ao Nuclear Power Station Phase II are larger than those of Ling’ao Phase I,the first column clearance from South Side column B to column A is bigger than that of Ling’ao Phase I in view of the installation requirements of turbine generator,condenser and deaerator.The main building of Ling’ao Nuclear Power Station Phase II is arranged as three floors,i.e.,bottom floor,intermediate floor and operation floor.A continuous ring-type channel is formed in the intermediate floor for the convenience of equipment manipulation and maintenance by patrol inspection personnel and the intermediate floor thus becomes wider and brighter.