The invention relates to an environment-friendly mixed working medium, a preparation method thereof and a device comprising the environment-friendly mixed working medium. The mixed working medium comprises a first component trifluoroiodomethane (R13I1), a second component 1, 1-difluoroethane (R152a), a third component isobutane (R600a) and a fourth component, wherein the fourth component is one ofthe propane (R290) or propylene (R1270); or the mixed working medium comprises the first component trifluoroiodomethane (R13I1), the second component fluoroethane (R161), the third component difluoromethane (R32) and the fourth component, wherein the fourth component is one of trans-1, 3, 3, 3-tetrafluoropropene (R1234ze (E)) or propylene (R1270). According to the present invention, the preferredlubricant polyalkylene glycol, stabilizer butylated hydroxytoluene and extreme pressure agent zinc dialkyl dithiophosphate can be added into the environment-friendly mixed working medium, so that theperformance and stability of the mixed working medium are enhanced. Meanwhile, the mixed working medium is good in environment performance, has the GWP lower than 100, enables the volume refrigerating capacity and the volume heating capacity to be greatly improved by 30% or above, and has the smaller temperature slippage.