Circuit and method for auto setting real-time clock of electronic device

The invention relates to a circuit for setting a real time clock of an electronic device automatically and a method thereof. The invention stores a retrieve program in an electronic device, and when the electronic device is connected with a main frame, the retrieve program is transmitted to the main frame for the main frame to execute the retrieve program, and a real time date, a real time or an activity postil of the main frame is retrieved and transmitted to the electronic device, so as to set a real time date, a real time, a warning date or a warning time of the real time clock of the electronic device. The invention can set the real time clock of the electronic device automatically and does not require the user to set the real time clock of the electronic device manually, thereby being convenient for the user to operate the electronic device and improving the convenience for using the electronic device.