A new type of X-ray diode (XRD-Ⅱ) with ultrafast response time was developed. XRD-Ⅱ detector was improved on the basis of old XRD (XRD-Ⅰ), and its performances were studied on the 8ps laser facility. The results show that XRD-Ⅱ has excellent high-voltage tolerance (to 6 kV) and super-fast response time ( rise time is about 40 ps, and full width at half maximum (FWHM) is about 80 ps when bias voltage is 5 kV). The detector calibration was carried out on Beijing synchrotron radiation facility, which shows that the detector’s sensitivity has not deteriorated.