Abstract: Disclosed herein is a mounting structure of a fuel rail, including a mounting boss part having a through-hole formed in a longitudinal direction and a first mating surface formed at an outer surface, an injector cup part provided separately from the mounting boss part and having a second mating surface formed at an outer surface and a flow path hole formed at one side of the second mating surface to be connected to the main pipe for transferring fuel to an injector, and a bridge part connecting the mounting boss part and the injector cup part and having a third mating surface. The mounting structure of the fuel rail can effectively distribute stress concentration by increasing contact area with the main pipe, thereby improving fatigue strength.