Mo/Si and SiC/Mg period multilayer mirrors are investigated for solar He-II radiation at 30.4 nm. The optical stabilities of these multilayers are measured before and after space environment simulation tests for the purpose of potential application in space extreme ultraviolet (EUV) observations. All these multilayers are deposited by magnetron sputtering method on microcrystalline glass substrates. Then thermal cycling stability and radiation exposure experiments are performed to simulate the space environment. The testing results indicate that the Mo/Si multilayer is more stable than the SiC/Mg multilayer. The reflectivity of the SiC/Mg multilayer decreases slightly.