Abstract: Beamforming is an effective spatial filter, In order to extend the covering range and filter waves from multiple directions at the same time, a digital interpolation beamforming with uniform linear array is designed, meanwhile the influence of array number and sampling frequency to drease synchronous beams is analyzed. In the end, the performance of digital interpolation beamforming which uses an uniform linear array with eight hydrophones is evaluated by computer simulation. The result shows that the method can generate synchronous beams effectively after the zero pads interpolation, so the whole beam space can be covered simultaneously, and the effect of interpolation is equal to increase the sampling frequency of the system.