The influence of the spin on the ground state energy of the strong coupling 2 D magnetopolaron was studied by using the linear combination operator method. Numerical calculation, with KI crystal as an example, illustrates that the ground state energy of the strong coupling 2 D magnetopolaron for the electron spin of different direction increases or decreases with increasing magnetic field. The ratio of electron spin energy to the ground state energy of the magnetopolaron increases with increasing magnetic field.