A method for processing a communication service in a circuit switch domain, executed by a device configured in a communication terminal, which comprises: a switching control module and 1 switching execution module, comprising: judging, by the switching control module, whether a switching condition is met, when a communication service being currently processed by the communication terminal is a voice call service or a short message service in a circuit switch domain, wherein the switching condition is a condition for switching the voice call service or the short message service onto a real-time communication tool in a packet switch domain; if the switching condition is met, notifying the switching execution module; and switching, by the switching execution module, the voice call service or the short message service onto the real-time communication tool in the packet switch domain, when the switching condition is met; and characterized in that: wherein when the communication service is a voice call service in the circuit switch domain, the switching condition is met if: the opposite terminal is in the address book of the real-time communication tool which has a voice call function and/or a video call function on the communication terminal; or the opposite terminal is in the address book of the real-time communication tool which has a voice call function and/or a video call function, and the communication terminal is in a networked state currently; wherein the switching the voice call service in the circuit switch domain onto the real-time communication tool in the packet switch domain comprises: initiating the voice call service and/or the video call service in real-time communication to the opposite terminal by the real-time communication tool which has the voice call function and/or the video call function on the communication terminal. judging, by the switching control module, whether a switching condition is met, when a communication service being currently processed by the communication terminal is a voice call service or a short message service in a circuit switch domain, wherein the switching condition is a condition for switching the voice call service or the short message service onto a real-time communication tool in a packet switch domain; if the switching condition is met, notifying the switching execution module; and switching, by the switching execution module, the voice call service or the short message service onto the real-time communication tool in the packet switch domain, when the switching condition is met; and characterized in that: wherein when the communication service is a voice call service in the circuit switch domain, the switching condition is met if: the opposite terminal is in the address book of the real-time communication tool which has a voice call function and/or a video call function on the communication terminal; or the opposite terminal is in the address book of the real-time communication tool which has a voice call function and/or a video call function, and the communication terminal is in a networked state currently; wherein the switching the voice call service in the circuit switch domain onto the real-time communication tool in the packet switch domain comprises: initiating the voice call service and/or the video call service in real-time communication to the opposite terminal by the real-time communication tool which has the voice call function and/or the video call function on the communication terminal. wherein when the communication service is a voice call service in the circuit switch domain, the switching condition is met if: the opposite terminal is in the address book of the real-time communication tool which has a voice call function and/or a video call function on the communication terminal; or the opposite terminal is in the address book of the real-time communication tool which has a voice call function and/or a video call function, and the communication terminal is in a networked state currently; wherein the switching the voice call service in the circuit switch domain onto the real-time communication tool in the packet switch domain comprises: initiating the voice call service and/or the video call service in real-time communication to the opposite terminal by the real-time communication tool which has the voice call function and/or the video call function on the communication terminal.