A kind of GaAs photoconductive detector (PCD) was used to measure the radiation pulse signal of fusion neutron.According to the PIN detection system, the GaAs direct radiation sensitivity by １４．１MeV neutron have calculated, the results is 1.5(10E-20 (1±１８％）C(cm(cm/mm(mm(mm.The difference of the measured result and the pcalculated value, the foreign report is very small respectively.