The present invention discloses an isolation circuit having test mechanism. An isolation circuit component performs signal transmission when a signal that a control terminal receives has an enabling state and performs signal isolation when the signal has a disabling state. The test circuit includes a multiplexer and a control circuit. Under a shifting operation state in a test mode, the control circuit controls the multiplexer to select an operation input terminal to receive and output an isolation control signal having the enabling state to the control input terminal. Under a capturing operation state in the test mode, the control circuit controls the multiplexer to select a test input terminal to receive and output the test signal to the control input terminal. The control circuit further determines whether the isolation circuit performs signal transmission or signal isolation according to the signals at the data input terminal and the data output terminal.