A dial system for steering wheel of an automobile includes two dials respectively mounted on the steering wheel and each having a first housing and a dial set received in the first housing. The dial set includes a number button and multiple functional buttons partially extending the first housing for being operated. A circuit board is received in the first housing for wirelessly transmitting signals when the buttons are operated. A second housing is mounted to the first housing to form a space for receiving the dial set and the circuit board. A battery seat with a battery is laterally inserted into the space for providing power to the circuit board. A controller is disposed on the automobile for receiving and processing the signals from the first dial and the second dial.