A metal-semiconductor composite with the interfacial shells is investigated theoretically for the large linear magnetoresistance effect of high doping Ag 2+𝛿 Se and Ag 2+𝛿 Te materials. The magnetoresistance (MR) of composites is a function of the magnetic field, temperature, the conductivities of two phases without magnetic field, and the thickness and conductivity of the interfacial shells. The MR increases with the increase of the magnetic field and with the decrease of temperature, and no saturation is found even under the high magnetic field. Moreover, it is interestingly found that the interfacial shell is an important factor for the MR of the composites. The MR increases with the thickness and the conductivity of the interfacial shells. Lastly, the theoretical results on the MR are compared with the experimental data. It is found that the value of the MR of the composite with the interfacial shell is larger than that without the interfacial shell.