电路交换（Circuit Switching）是相对于封包交换（或称分组交换）的一个概念。电路交换要求必须首先在通信双方之间创建连接信道。在连接创建成功之后，双方的通信活动才能开始。通信双方需要传递的信息都是通过已经创建好的连接来进行传递的，而且这个连接也将一直被维持到双方的通信结束。在某次通信活动的整个过程中，这个连接将始终占用着连接创建开始时，通信系统分配给它的资源（信道、带宽、时隙、码字等等），这也体现了电路交换区别于分组交换的本质特征。

Circuit switching is a methodology of implementing a telecommunications network in which two network nodes establish a dedicated communications channel (circuit) through the network before the nodes may communicate. The circuit guarantees the full bandwidth of the channel and remains connected for the duration of the communication session. The circuit functions as if the nodes were physically connected as with an electrical circuit.