Abstract: China Integral Reactor Plant（CIP） is a light water cooled,300MWe power reactor under development by Chinese National Key Laboratory of Reactor System Design Technology.CIP features an integral reactor vessel that contains the CRDM and all the major reactor coolant system components including the reactor core,the coolant pumps,the once-through steam generators and the pressurizer.This integral design approach eliminates the large coolant piping and large LOCAs,and thus provides with higher level of securities.This paper introduces the selection of the CIP containment system,the design of containment,the determination of the design pressure for the containment and the calculation analysis of the containment structure.