Abstract: With the development of space technique, the space systems are becoming more and more complicated, but they are more and more susceptible to space weather. Consequently, space weather forecast is being widely researched in the world. The great impacts on the normal life of human made by space weather are presented in this paper. The importance about solar X-ray imaging in space weather forecast is expatiated on. The fundamental principle, the principal design and the instrument characteristics of celestial and solar X-ray grazing imager operating successfully in space are introduced. The principal technical indices of solar X-ray imaging telescope (SXIT) which is being developed in China are presented. The SXIT integrates the gracing incident telescope and the normal incident telescope and operates in the 0.4--10 nm X-ray band interval and the 19.5 nm EUV band. It can provide the high resolution solar disk imaging for its 45 arcmin field of view and 5 arcsec spatial resolutions. The SXIT is the newest solar storm monitor at present. The SXIT extends the temperature response to the coronal plasma and enhances the sensitivity to the coronal plasma with lower temperature, so more signatures and precursors of the solar eruption can be observed by the SXIT. The SXIT is dedicated to domestic space weather forecast. It will firstly fly on the FY-4 serial meteorological satellites that operates on a geostationary orbit, so real-time data for space weather forecast can be obtained 24 hours per day. The SXIT will greatly enhance the ability of the domestic space weather forecast and the research of solar physics if it operates successfully on orbit.