The scheme of barnes interpolation with pre-clipping wight matrix of the geographical boundaries is proposed to achieve interpolating surface meteorogical observation data into the grid field. first to use numerical differentiation method and seed filling method to obtain the clipping matrix of geographic boundaries, and multiply with the barnes interpolation weight matrix to form the constant pree-clipping weight matrix geographical boundary which is used in the latter grid interpolated analysis. the scheme can not only improve the quality of graphical analysis, but also omit the step of graphical clipping in the plotting process of GIS (geographic information system) which greatly shotens the time cost of graphical alaysis product. the scheme has been well comfirmed in the service application.