CMMB is the abbreviation of China Mobile Multimedia Broadcasting. At present, CMMB system mainly provides video broadcasting service. With the restriction of hardware, only the terminal with the CMMB module can receive CMMB video program. A digital TV broadcasting system based on CMMB is presented. The framework of system and the design of all parts are expounded. The implementations of the key technologies and algorithms are explained in detail. Experiments show the system is able to accomplish broadcasting of the digital TV based on CMMB and share watching digital TV program under Windows, Linux, Symbian operating systems. It extends the function of general intelligent device and reduces the costs and resolves the problem of CMMB poor indoor signal coverage.