A magnetic integrated device is disclosed, the device includes: a first magnetic core base and a second magnetic core base that are parallel and a first magnetic core column, a second magnetic core column, and a third magnetic core column that are located between the first magnetic core base and the second magnetic core base; and a first winding, a second winding, and a third winding are wound on the first magnetic core column, the second magnetic core column, and the third magnetic core column respectively in a same manner to form a closed magnetic flux loop, where the first winding, the second winding, and the third winding are separately used for connecting to a branch of a three-phase parallel circuit, and in all branches of the three-phase parallel circuit, values of currents are the same, and a difference between each two current phases is 120 degrees.