In this paper, we design and fabricate a new test structure of bipolar device. A gate is deposited on the oxide layer covering the base region of normal lateral pnp bipolar transistor. The characteristic of drain current (collector current) versus the gate voltage is recorded by sweeping the voltage applied to the gate, then the subthreshold-current technique is used to separate the radiation induced oxide trapped charges and interface traps in the gate controlled lateral pnp bipolar transistor during 60Co- irradiation. The test structure and the measurement of the bipolar transistor used in the experiment are introduced in detail in this paper.