In this paper, a pulse-dilation framing tube is developed, and the field curvature characteristics and off-axis spatial resolution of this tube are analyzed. Multiple short magnetic lenses are used in this tube to image the photoelectrons from the cathode onto the receiving surface of the microchannel plate. The field curvature characteristics of lenses number imaging are studied by simulations and verified by experiments. The simulation results show that the field curvature of the imaging system can be reduced by multiple lenses and the spatial resolution is improved. When the imaging ratio is 1∶1, the axial deviations of simple lens, bilens, triplet lens, and four lenses from Gaussian image plane are 13 cm, 4.7 cm, 2.5 cm, and 1.7 cm, respectively. The experimental results show that the off-axis modulation of the four lenses system is 40% higher than that of the single lens.