ECPR (electrically calibrated pyroelectric radiometer) is a kind of electrical substitution radiometer with high precision in detecting optical power. With the development of the enhanced UV ECPR, a measuring system for the absolute spectral response of UV detector is built. The paper introduces the measuring methods of UV absolute spectral response based on ECPR, the configuration of the measuring system and the measurement results. The feature of the system is high precision, easy operation and automation. Also it provides a good solution for the measurement of absolute spectral response of UV source.