A Landau Pekar variational theory is employed to study the properties of strong coupling surface magnetopolaron.The ground state energy and the effective mass of strong coupling surface magnetopolaron are calculated respectively,and the relation of the ground state energy,the vibration frequency and the effective mass of surface magnetopolaron to magnetic field are discussed.Numerical calculations for KCl crystal,as an example,are performed.The result illustrates that the vibration frequency and the effective mass of a strong coupling surface magnetopolaron will increase with increasing magnetic field and the ground state energy will decrease with increasing magnetic field.