Abstract: In this paper,the Single Event Effect test was carried out on a domestic radiation-hardened SPARC-V8-microprocessor in high/low speed modes.The Single Event Function Interrupt threshold and cross-sections were got through the experiment,and the error rate at the GEO orbit was evaluated.The contrast and analysis show that domestic and foreign CPUs have the same order in SEE indicators.The anti-SEE ability of the CPU in the high speed mode (cache-on) is twice better than that in the low speed mode.