The inertial confinement fusion experiment requires framing tube to have picseconds temporal and micrometer spatial resolution. Although the temporal resolution is promoted to ~10 ps by pulse-dilation technology, the spatial resolution is descended by the single magnetic lens. In order to promote spatial performance, the imaging system of tube is design using telescopic imaging technology, the spatial resolution is simulated by the imaging distribution and the Rayleigh Criterion, and the influence of telescopic system on spatial resolution is analyzed. The research results show that telescopic system is can promote the spatial performance of tube, which is made up of two magnetic lenses. The smaller the focal length of telescopic system is, the better the spatial resolution is. The conclusion can provide a theoretical support for designing framing tube with the large object plane.