Provided are a test circuit, a test device and a test method thereof. The test circuit includes: a signal processing module configured to receive a pulse signal to be tested and output a processing signal under a control signal; a sampling module connected to the output terminal of signal processing module and configured to receive the processing signal and generate a sampling signal according to the processing signal. The sampling signal includes a first sampling pulse and a second sampling pulse, the first sampling pulse and the second sampling pulse have a pulse width difference, the pulse width difference is equal to the pulse width of the pulse signal.