Abstract: In order to solve the uncertainly tof the element place for a towed line array,the sample matrix of the signal and the time-space curve equations of the array shape are given in the paper.Average beampatterns of a randomized processing and quantitative result of the loss caused by the array shape distortion are obtained.A model used for estimating array shape is given,the experimental study of dynamical beamforming has been practised.The results show that 4dB gain improvement can be obtained by dynamic compensation for a small towed line array,when the distortion of array shape is medium and towed speed is show.