In order to overcome the disadvantages of the traditional LP (Linear Prediction) algorithm that brought the cumulation of prediction errors in the process of building a virtual array, a kind of improved LP algorithm was proposed, with which we could make full use of the information of the real array in the virtual array building. Respectively through the actual array method, the traditional LP virtual array method and the improved LP virtual array method, the beam performance of assumed array was simulated and the data from lake trial was dealt with to form the imaging of echo highlights. Result shows that the improved LP method is more effective than the traditional LP method in suppressing the side-lobe of wave beams, and further improves the angle resolution and array gain. And when the improved LP method is applied to practical engineering for bottom target detection under specific experimental background, the directional resolution accuracy can be increased by 75%.