Mn₃(Cu_0.6Si_0.15Ge_0.25)N/Ag composites were prepared by mechanical ball milling and solid state sintering.The thermal expansion coefficients, electrical conductivities and thermal conductivities of Mn₃(Cu_0.6Si_0.15Ge_0.25)N/Ag composites were studied in the temperature range from 77 K to 300 K.All samples with Ag amount of 1.5, 10 and 20 wt%show negative thermal expansion (NTE)within an effective temperature range from 205 K to 275 K.It is interesting to find that the effective temperature range of NTE moves toward room temperature and becomes narrower with the i13- crease of Ag content.Furthermore, Mn₃(Cu_0.6Si_0.15Ge_0.25)N/Ag composite exhibits a higher electri—cal conductivity of 1106(Ohm·m)^-1 and thermal conductivity of 10.5 W/(mK)than that of Mn₃(Cu_0.6Si_0.15Ge_0.25)N.