A synchronous moving double-axis hinge comprises a support member, a first transmitting assembly and a second transmitting assembly mounted onto the support member, and a transmission element installed on the support member. The first transmitting assembly includes a first transmission shaft and a first helical gear. The second transmitting assembly includes a second transmission shaft and a second helical gear. The transmission element includes a hinge pin and a driven helical gear. The driven helical gear has a first engaging zone to engage with the first helical gear and a second engaging zone to engage with the second helical gear. The hinge pin has a third extension axis crossing with a first extension axis of the first transmission shaft and a second extension axis of the second transmission shaft. Thus the crossed helical gears can effectively amplify the contact among the gear teeth to make transmission steadier.