We analyze and compare the existing designs of SX-700 beamline in this article and describe a new version of the SX-700 beamline in which we make some improvements on SX-700 designs mentioned before [1-4]. The new design uses a plane elliptical pre-mirror which deflects the SR beam vertically to compress the SR source onto the entrance slit and uses an ellipsoidal mirror to focus the monochromatized light. By proper selection of design parameters, the beamline produces non-astigmatic and nearly aberration free images like the improved SX-700 beamline by Nyholm et al. . But our design has the following advantages: (1) our plane elliptical pre-mirror is much smaller, (2) an entrance slit is put in the beamline, and (3) the beamline is suitable to be installed at high energy electron storage rings.