Abstract: The technique of transient calibration of acoustic transducers is investigated.The low frequencyAnit imposed by confined water tank is prominently reduced by applying Prony's model to the sampled transient data.In this paper,a new conception that the fluctuation of transmitting characteristics of transducers may be compensated by using devised minimum phase signals is presented to improve the calibration accuracy of transducers with unflat transmitting response.And its effectiveness is demonstrated in both simulated and actual experiments.