A soft X-ray detector has been made with high quality chemical vapor deposited(CVD) diamond and the electrical structure of micro-strip. Through the measurement of response time on a laser with the pulse width of 10 ps, the full width at half maximum of the data got in the oscilloscope was 115 ps. The rise time of the CVD diamond detector was calculated to be 49 ps. In the experiment on the laser prototype facility, the signal got by the CVD diamond detector was compared with that got by a soft X-ray spectrosmeter. Both signals coincided well. The detector is proved to be a kind of reliable soft X-ray detector with fast response and high signal-to-noise ratio.