Abstract: The present paper deals with theoretical model of random sequence of exponential attenuate acoustic pulses caused by ship propeller cavitation noise.On the basis of above theoretical model,the spectrum formula of propeller cavitation noise has been derived.It is shown that propeller cavitation noise is composed of continual spectrum and separable line spectrum.The line spectrum relative amplitude ofpropeller cavitation noise is depended on random swing of acoustic pulse front edge generation moment.At high frequency line spectrum components in noise approach to zero,and in lower frequency region line spectrum was much large than correspondent continual spectrum.The continual spectrum decreasewith frequency as inverse square law at high frequency,and increases with frequency square in lowerfrequency,and the spectrum peak is existed in certain lower frequency.The agreement between abovementioned theoretical results and existent measured data is very good.