The influence of the magnetic field and temperature on the properties of the strong-coupling magnetopolaron in an asymmetric quantum dot is studied by using the Tokuda’s linear-combination operator and the Lee-Low-Pines variational method. The expressions for the vibration frequency λ, ground state energy E0 and the effective mass m* of the magnetopolaron as a function of the transverse effective confinement strength ω1, the longitudinal effective confinement strength ω2, the electron-phonon coupling strength α, the cyclotron frequency ωc and the temperature parameter γ are derived. Numerical results indicate that λ and m* of the magnetopolaron will increase with increasing ω1,ω2,ωc and α, and will decrease with increasing temperature T. The value of E0 changing with ω1,ω2,ωc,α and γ are srongly related to the propties of the state of the magnetopolaron. The signs of positeve and negative E0 relate not only to the value of ω1,ω2,ωc and α but also to the value of γ. However, only on the condition of higher temperature (γλ,m* and E0 of the magnetopolaron is obvious.