Abstract: Experimental methods are emphatic ally described for Single Event Effects (SEE) experiments on semiconductor devices using accelerators. The particle beam from the accelerator can be scattered and reduced by several orders of magnitude with an Au foil. A novel system is designed for measuring the very low proton beam and a method is founded for measuring the uniformity of the proton flux. The proton Single Event Upset (SEU) cross section is of the order of 10- 14cm2·bit- 1 for Static Random Access Memories (SRAMs). The SEU heavy ion LET thresholds are 4～8MeV·cm2·mg- 1 and the saturation SEU cross sections are of the order of 10- 7cm2·bit- 1. Hard error in single bit and functional error in SRAMs and Single Event Latch-up in 80C86 are observed in proton experiments.