Solar flares with enhanced X-ray emissions usually produce excess ionizations in the ionosphere and cause what generally known as sudden ionospheric disturbances (SID). It has long been established that much of information on the X-ray emission can be based on the observation of SID's. In recent 20 years, although direct observations of the X-ray radiation by satellites have made quantitative data available, SIDmeasurements are still a useful tool, because the method iscomparatively simple, easy to give a quick and continuous patrol.In this paper a sweep frequency device was described for the continuous monitoring of SID's. Emphasis was put to the application of the records in solar X-ray 'flare studies. Analysis of the data from 1982-1983 showed that the method is sensitive to solar flare with X-ray enhancement. Its records of SID's are in very good agreement with those reported by some other stations in the world with different methods except a few small sized disturbances. This shows a reliability of the data. Furthermore, most of the solar soft X-ray (1-8 À) events with a peak flux larger than about 10-3
, can be recognized from the records. The possibility of quantitative study of solar X-ray flux and its time curves with this kind of data were briefly discussed.