Abstract: The uniformity of the magnetic field inside the current carrying ellipsoid coil is studied by using digital image method. Using the outstanding numerical calculation ability and digital drawing function of  MATHEMATICA，the three-dimensional diagrams of the magnetic field from a sparse winding ellipsoidal coil are 　　plotted. The ellipsoidal regions corresponding to a variety of uniformity are preformed. The irrationality of the cylindrical uniform area in the existing literature is pointed out. A reliable and convenient method for the research on the electromagnetic field uniformity is provided

Key words: sparse winding ellipsoidal coil, magnetic field, uniformity and ellipsoidal region, numerical analysis