An identification code circuit for a receiving coil in a magnetic resonance imaging system, is embodied in a main coil. The circuit has a fixed resistance for generating the identification code of the main coil. The main coil has a socket for connecting a sub-coil, so that a coil plug of a sub-coil can be plugged into the socket for connecting to the main coil. The identification code circuit also has a regulating resistance and a sub-coil switch corresponding to the socket. The coil plug of the sub-coil is plugged into the socket to close the sub-coil switch, so that the values of the regulating resistance and said fixed resistance are added together to form a combined resistance value. After said main coil has been connected to a magnetic resonance imaging system, an identification code source voltage value across the combined resistance value is the identification code of the combined main coil and sub-coil. A receiving circuit identification code thus can be generated simply and with reduced cost.