CRMX86 operating system is developed on the basis of improving iRMX86 real-time，multi-task operating system. CRMX86 provides a set of functions of the Chinese information processing，has the advantage of high efficiency and is configurable. CRMXDBMS is a relational database management system supported by CRMX86 operating system. It is even better than dBAS-E-Ⅲ. CRMXDBMS has two ways of enciphering user-data and a nice user interface. In this paper the basic structures and main techniques in designing CRMXDBMS system.