The electron transport properties of(GaAs)_4 atomic chain coupling graphene ribbon was calculated using density functional theory and non-equilibrium green's function from the first principles.The results showed that changing the distance of atomic chain with the graphene can modulate electron transport properties of system.As the distance changed in the range of 0.10-0.28 nm,electrons transported in graphene and atomic chain have an influence on each other.The equilibrium conductance of(GaAs)_4 atomic chai...