High-precision x-ray imaging diagnostics of hotspot at the stagnation stage are essential for regulating implosion asymmetry and retrieving physical implosion parameters. With regard to 10-20 keV energy band imaging, existing diagnostic instruments such as Kirkpatrick-Baez microscopes and pinhole cameras are insufficient in terms of spatial resolution and collection efficiency. The situation is even worse when high-speed, time-resolved imaging diagnostics are performed by coupling framing cameras or line-of-sight imagers. This article presents the basic principles and optical system design of a 17.48 keV modified Wolter x-ray microscope, to resolve the problems encountered in high-energy imaging diagnostics. The proposed optical configuration offers a better spatial resolution, greater depth of field, and preliminary compliance with the requirements of high precision optical processing techniques. The spatial resolution is better than 1 µm in a field range ±150 µm, and is better than 3 µm in a total field of view ∼408 µm in diameter. The geometric solid angle is calculated as 3.0 × 10-5 sr and is estimated to be 1.2 × 10-6 sr, considering the reflectivity of the double mirrors. The proposed microscope is expected to effectively improve spatial resolution and signal-to-noise ratio for high-energy imaging diagnostics.