The invention provides a hand-held electronic apparatus and a method for protecting the system circuit. The hand-held electronic apparatus comprises: a shell, a system circuit, a removable battery and a protecting circuit. Both the system circuit and the protecting circuit are set it the shell. The removable battery is selective combined with the shell. The removable battery has an electric connection with the system circuit and form a circuit to provide power for the system circuit when the removable battery combined with the shell. The protecting circuit comprises a protecting control circuit and a control switch. The control switch is set on the circuit loop. The protecting control circuit will send out a protecting control signal to the control switch when it detects the abnormal voltage or current in the circuit loop to prevent the system circuit for being damaged by the abnormal voltage or current.