a method and system for multicast broadcast service over mobile multi - hop relay network using dynamic modification of modulation and coding scheme level are provided . the base station of the system for mbs over mmr network using dynamic modification of mcs level comprises : adaptive modulation and coding table for storing the mcs level for the transmission between the bs and relay station , throughput corresponding to the mcs level , and spectrum efficiency corresponding to the mcs level ; and dynamic modulation and coding table for storing the mcs level for the transmission between the rs and ms to be changed upon update of the amc table . if there is any change of the mcs level for the transmission between the rs and ms , the bs transmits a mcs control message to the rs informing of the mcs level change such that mbs data is transmitted with the changed mcs level .