The negative thermal expansion (NTE) and structural evolution of antiperovskite compounds Mn3Ga1-xGexN (0 x 1.0) were systematically investigated. Our results indicate the crystal structure of Mn3Ga1-xGexN changes from cubic (C) to tetragonal (T-4) with increasing Ge content by X-ray diffraction (XRD).The negative thermal expansion from x = 0 (operation-temperature range T = 20 K) to x = 0.4 (T = 60 K) becomes broad and shifts to higher temperature, and then it became positive from x = 0.5 in Mn3Ga1-xGexN. Typically, Mn3Ga0.5Ge0.5N shows low thermal expansion behavior between 300 and 450 K (T = 150 K), and thermal expansion coefficient is estimated to be 2 x 10(-6) K-1. Furthermore, variable temperature XRD was measured to reveal the origin of NTE. The cubic I - cubic II phases coexistence (x = 0.2) and cubic I - tetragonal coexistence (x = 0.5, 0.6) was observed at low temperature. The tunable NTE is highly valuable for practical applications in precision devices.