The invention discloses a multichannel synchronous output calibrating apparatus and method. The calibrating apparatus includes a clock module, a clock time delay module, a waveform generation module,a pulse shaping module, a logic AND gate module, a pulse width measurement module and a synchronous control module, wherein an inter-channel synchronous time delay error is obtained by adopting the pulse shaping module, the logic AND gate module and the pulse width measurement module. The circuit structure is simple, the hardware implementation is easy, the complex calculation is avoided, an ADC circuit and a high-performance calculation module do not need and the cost is low; when the error is corrected, the calibrating apparatus adjusts a time delay and a waveform phase of a sampling block sequentially via the clock time delay module and the waveform generation module until the inter-channel synchronous time delay error reaches to a designed requirement, so the precision is high and thechannel consistency is good; and in additional, since a cooperative manner of precise time delay adjustment and edge inspection is adopted by the pulse width measurement module, a pulse width measurement error is effectively reduced.