Abstract: Because the small size of recording dots in quantum magnetic disk,it is very difficult to measure the magnetic field numerical distribution using the ordinary method.To prove the feasibility of quantum magnetic disk,magnetic-field distribution of quantum magnetic disk is calculated by finite element method (FEM) software. On the assumption of the magnetization direction is horizontal,we obtain 2D magnetic field distribution of circle quantum dots with diameter 20 nm and distance 10 nm and that of square quantum dots with edge 20 nm and distance 20 nm.It is proved that the magnetic fields distribute periodically and the length of period is the length of dot plus the distance between the dots.This calculation could be a good reference for the reseach of quantum magnetic disk.