Abstract: A circuit and operating method for an integrated interface of a PDA and a wireless communication system are disclosed. The circuit includes a PDA-turn-on-wireless-communication-system signal line, a PDA-reset-wireless-communication-system signal line, a PDA-state signal line, a wireless-communication-system-state/wake-up-PDA signal line and two serial ports, wherein the serial ports are electrically connected between the PDA and the wireless communication system, and one of the two ports is used to transmit control signal and status data, another one of the two ports is used to transmit digital data signals. Moreover, the PDA-turn-on-wireless-communication-system signal line and the PDA-reset-wireless-communication-system signal line makes the PDA able to turn on and reset the wireless communication system, respectively. The PDA-state signal line and the wireless-communication-system-state/wake-up-PDA signal line transmit the status of the PDA and wireless communication system to each other.