The high-pressure structural, vibrational and electrical properties for realgar were investigated by in-situ Raman scattering and electrical conductivity experiments combined with first-principle calculations up to similar to 30.8 GPa. It was verified that realgar underwent an isostructural phase transition at similar to 6.3 GPa and a metallization at a higher pressure of similar to 23.5 GPa. The isostructural phase transition was well evidenced by the obvious variations of Raman peaks, electrical conductivity, crystal parameters and the As-S bond length. The phase transition of metallization was in closely associated with the closure of bandgap rather than caused by the structural phase transition. And furthermore, the metallic realgar exhibited a relatively low compressibility with the unit cell volume V-0 = 718.1.4 angstrom(3) and bulk modulus B-0 = 36.1 GPa.