The utility model provides a detecting device based on an analog quantity input combining unit, which comprises the following components: an input component which is connected with an ARM chip and is used for transmitting a command signal to the ARM chip; a standard clock component which is connected with the ARM chip and is used for transmitting a standard clock to the ARM chip; the ARM chip which is connected with a signal source and a detected combining unit respectively and is used for transmitting a second pulse to the detected combining unit and transmitting a signal parameter and a digital signal to the signal source; the signal source which is connected with the detected combining unit and is used for receiving the signal parameter and transmitting a standard signal to the combining unit and the ARM chip according to the signal parameter and the digital signal; and a network message analyzer which is connected with the detected combining unit. The detecting device can quickly and accurately realize the following tests: accuracy test of the combining unit, ECT/EVT communication interface test, sampling value output interface performance test, clock synchronizing test and network environment effect test.