The properties of bound magnetopolaron with strong electron-LO phonon coupling were studied using a linear combination operator and a unitary transformation method in an asymmetry quantum dot. The ground state energy of strong-coupling bound magnetopolaron was obtained in an asymmetry quantum dot and the effects of the transverse and longitudinal confinement lengths of quantum dot, the ground state energy of magnetopolaron , the electron-phonon coupling strength and the external temperature on the ground state lifetime of magnetopolaron were discussed. Quantum transition which causes the changes of the magnetopolaron lifetime is occurred in the quantum system due to the electron-phonon interaction and the influence of external temperature which is the magnetopolaron leap from the ground state to the first-excited state after absorbing a LO-phonon. Numerical calculations are performed and the results show that the ground state lifetime of bound magnetopolaron is extended with the rise of the ground state energy, and shortened with the electron-phonons coupling strength, the transverse and longitudinal confinement lengths of quantum dot , and the external temperature.