The invention discloses a medium-voltage switchgear by employing trifluoroiodomethane and a mixture thereof as an insulating medium. The medium-voltage switchgear comprises a sealing box body shell provided with an electrical assembly at the inside and a dry insulating medium inflated in the sealing box body shell, and the inflation pressure of the insulating medium is 0.1 MPa-0.3 Mpa; the sealing box body shell is manufactured by laser welding of metal sheet parts, and the metal sheet parts comprise demagnetization stainless steel materials with types of 309, 310, 314 or 330; when the operating environment in which the medium-voltage switchgear is located is higher than or equal to -20 DEG C, the insulating medium is trifluoroiodomethane; and when the operating environment in which the medium-voltage switchgear is located is lower than -20 DEG C, the insulating medium is the mixture of trifluoroiodomethane and auxiliary gas, wherein the mixed volume ratio of the trifluoroiodomethane is lower than 40%, and the mixed volume ratio of the auxiliary gas is higher than 60%. The beneficial effects of the medium-voltage switchgear are that good insulation is realized, and the environmental performance is greatly improved.