In order to solve the problem of finding the optimal survey line for multibeam bathymetric sounding seafloor technology, the constraints of the survey line program are obtained by reviewing the information. The function is constructed by geometric relationship, sine theorem, trigonometric function, system construction, space vector and other methods with the background of sloping seafloor surface. The idealized line is first analyzed and then the angle between the line and the normal projection of the sea floor is introduced and gradually realized. The overlap rate formula derived according to the meaning is analyzed by graphing in the new context, and finally the inference is combined to convert the three-dimensional spatial body into a two-dimensional planar problem through the conversion of the top view perspective, set up the equation of the survey line by establishing a planar right-angle coordinate system; construct the most value function according to the clamping angle situation and discuss it in sections, and finally get the main function and constraint function as well as the result graph of the actual context.