Current responsivity is an important characteristic of UV detector which cannot be measured directly after the coupling between detector array and readout integrated circuit (ROIC) chip. It’s very significant on the measurement for current responsivity of UV Focal plane array (FPA) detector. The 128×1 ROIC chip were measured. The integration capacitance and gain of source follower of ROIC chip were analyzed. Then, 128×1 AlGaN photosensitive chip and 128×1 UV FPA detector were tested by using a special system which was developed independently for high-accuracy measurement of UV detector. An indirect test method for current resposivity of UV FPA detector was studied and set up. The current responsivities by testing photosensitive chip directly were basically consistent with those by testing UV FPA indirectly. The relative deviation is about 5%. This test method is very easy and reliable, so can provide significant parameters to the comprehensive evaluation of UV FPA.