The powders of n-type (Bi1-xAgx)2(Te1-ySey)3 thermoelectric materials were synthesized by mechanical alloying and consolidated by spark plasma sintering. The milled powders were investigated by XRD and SEM, which shows that the pure Bi, Te, Ag and Se particles were alloyed after milling for 2h. With the increase of the time of mechanical alloying, the size of the powder grains decreases to about 1—0.5 μm. The effects of the doped elements on the thermoelectric properties have been studied. It was found that Ag can improve the power factor and decrease the lattice thermal conductivity, the compound (Bi0.99Ag0.01)2(Te0.96Se0.04)3 after milling for 10h possesses the highest value of the power factor and minimum thermal conductivity, which results in the highest value of ZT of 0.52 at 323K.