Abstract: To study the displacement damage effects, the proton accelerator and the neutron nuclear reactor are used to determine the displacement damage of compound semiconductor devices and silicon devices used for spacecraft. The curves of the degradation vs. the equivalent dose of the CTE of the GaAs optocpupler and the current amplification(h_FE) of the silicon transistors are obtained. By analyzing the radiation test data for the optocoupler and the bipolar transistor, it is concluded that the displacement damage equivalence for the silicon devices is no longer valid for the GaAs compound devices, thus a correction is needed. Empirical correction coefficients are then determined according to the test data.