The new concept and method of marine sounding correction are presented for the first time in which sounding and its correction can be merged into an organic whole. Nowadays main problems in marine sounding have been transferred from positioning to sounding field because of wide applications of GPS. Based on the above new concept and method, a new idea of developing a marine three-dimensional surveying instrument is further given in this paper, which is very important, significant and beneficial to the future bathymetric surveying in the world.