UV enhanced electrically calibrated pyroelectric radiometer (ECPR) is a kind of radiometers with high precision in UV radiation measurement. The basic principle is the electro-optical equivalence. When the pyroelectric detector reaches heat balance through optical and electrical signal heated surface alternately, optical power can be got if measuring the electrical power at this point. This paper presented an optical and electrical signal collecting system based on MCU and A/D device, which can measure the electrical power. Namely, the optical power value can be obtained by this method.