We present a structural characterization of solid germane (GeH4) under pressure from first-principles calculations. We find that this material undertakes a structural transformation from its low-pressure P21/c phase to high-pressure Cmmm phase at about 15 GPa where insulator-metal transition occurs, followed by two other metallic phases having the P21/m and C2/c structure at up to 200 GPa. Our results indicate that the metallization of GeH4 can be realized through band overlap within the material itself.