Abstract: In order to obtain better performances of detection and direction finding of long distance multiple targets, the split linear array with large interval between the sub-arrays is designed based on the MVDR beam forming which is widely used in engineering.The application of extended array aperture improves the acutance of spatial spectrum peaks.On the other hand,the incorrelate signal method(ISM) wideband MVDR pre-processing algorithm has been presented.Because widths and intervals of grating lobes introduced by divided sub-arrays vary with sub-band,the corresponding ambiguous peaks are counteracted while incorrelate sub-band MVDR spectrums overlapped.Finally the processing results of sparse array and wideband ISM beam forming compensate each other.Computer simulation and the lake authentication show the scheme put forward can improve the detection and resolution performance to underwater targets compared with uniform linear array(ULA) applied wideband MVDR and split linear array applied cross-correlation.