Abstract: A gate-controlled lateral PNP bipolar transistor has been manufactured by means of depositing a gate electrode on the oxide layer above the active base region of the conventional lateral PNP bipolar transistor, whose base surface potential can be adjusted by changing the bias condition of the gate. Neutron radiation effect experiments have been accomplished on the gate-controlled lateral PNP bipolar transistors whose bias voltage of the gate is zero, -10 V and 10 V respectively to investigate the influence of base surface potential on neutron displacement degradation rate. The experiments have been performed at Xian pulsed reactor and the neutron fluence is 21012, 41012, 61012, 81012, 11013 cm-2, respectively. The results indicate that the increased base surface potential makes the change of the reciprocal of the common emitter current gain degrade with neutron fluence more rapidly and the decreased base surface potential has no obvious influence on the degradation rate.