High-Tc superconductors have become a hot topic in physics since superconducting mercury was first reported more than a century ago. Dense hydrogen was predicted to metalize and become a superconductor at high pressure and room temperature. However, no widely accepted experimental work has been reported yet. In 2004, Ashcroft predicted hydrogen-dominant hydrides could become a high-Tc superconductor at high pressure, due to chemical precompression. Later, Drozdov et al. observed the superconductive transition of H2S at 203 K and 155 GPa, which broke the highest Tc record. Very recently, LaH6 was reported to show superconducting behavior at ~260K. Motivated by these efforts, extensive investigations on hydrides system have been reported.