Curvilinear-axis electron optical focusing and aberration theory of wide electron beams in immersion magnetic lenses, which can be used for projection electron beam lithography, are put forward, and second-order aberration formulas have been derived using the symbolic manipulation software MATHEMATICA(R). A program was written to calculate numerically the wide beam Gaussian focusing and aberration properties of these lenses by using the curvilinear-axis theory. The magnetic structures that have convergent force lines have been studied. As an example, lenses with an analytical axial magnetic field distribution are calculated. The results show that wide beam projection images without crossovers can be formed with demagnified lateral magnification, and with a submicron and nanometer lateral resolution over a larger field size.