Theoretical and experimental research of the spatial resolution characteristics of magnetic focusing framing tubes with single magnetic lens, double magnetic lenses and triple magnetic lenses are simulated and studied by Monte Carlo method, finite difference method and finite element method. The relationship among the number of short magnetic lenses and the surface curvature of Micro-Channel Plate(MCP), imaging range and rotation angle is studied. The results show that the more the number of short magnetic lenses, the smaller the curvature of the imaging surface, the flatter the image surface. The imaging range increases with the increase of the number of short magnetic lenses; the electron rotation angle at the MCP point decreases with the increase of the number of short magnetic lenses. With triple magnetic lenses, the spatial resolution of the framing tube is 10 lp/mm within the diameter of 36 mm.