An intake system of an engine for a vehicle, may include a surge tank including a first flange, and an intake manifold including a second flange connected with the first flange of the surge tank, wherein the intake manifold may include a main body including a fuel rail and intake ports corresponding to cylinders, and a guide member provided on the main body to guide the surge tank coupled with the main body in a direction where the surge tank becomes separated and more distant from the fuel rail of the intake manifold when a vehicle collision occurs.