The negative thermal expansion (NTE), magnetic and electronic transport properties of Mn3Ga1-xAgxN (0 ≤ x ≤ 1.0) with antiperovskite structure were systematically investigated. Our results indicate that the introduction of Ag in Mn3Ga1-xAgxN can effectively tune the coefficient of NTE from –232.57 × 10−6/K (x = 0, △T = 22 K) to −19.76 × 10−6/K (x = 1.0, △T = 15 K). Correspondingly, the ΔStotal associated with the different amplitude of the lattice contraction at the phase transition gradually decreases from 23.9 J/(kg·K) to 10.9 J/(kg·K) with increasing Ag content. The substitution of Ag in Mn3Ga1-xAgxN also affects significantly the magnetic properties and results in the magnetic evolution from antiferromagnetic (AFM) to ferrimagnetic (FIM) with increasing Ag content. Thus the magnetic transition from ferromagnetic to paramagnetic was observed at high doping level (for x = 0.8 and 1.0). Above transition temperature, the temperature coefficient of resistivity (TCR) can be tuned by Ag substitution and the lowest TCR value is 148.1 ppm/K when x = 0.8. The possible mechanism for the observed tunable TCR is discussed. The obtained results are helpful for understanding the chemical doping effects on the physical properties and the strong correlation effects in Mn-based antiperovskite compounds.