Acetylene（C

2

H

2

） is one of the most important fault characteristic gases in oil-immersed transformer discharge faults. The concentration and production rate can effectively reflect the insulation performance of oil-paper power transformer. In order to realize the effective detection of C

2

H

2

characteristic gas in oil

a method for the detection of characteristic gases in oil by metal-doped molybdenum sulfide（Mo S2） based semiconductor gas sensor was proposed. Based on the first principle

the adsorption properties of C

2

H

2

by intrin

sic and noble metal（Au and Ag） doped MoS

2

materials were calculated. The adsorption properties

such as adsorption energy

charge transfer

and electron state density

were calculated and compared. The results show that the adsorption of C

2

H

2

by doped MoS

2

is chemisorption

while the intrinsic MoS

2

shows physical adsorption characteristics

the strength relationship is in the order of Au-MoS

2

> Ag-Mo S2 > MoS

2

. The results of theoretical calculation of adsorption characteristics are conducive to the improvement of gas-sensing mechanism of MoS

2

materials and lay a foundation for sensor detection of characteristic fault gases in oil.