Abstract: For the single bit quantum information transfer in a spin chain, if the Hamiltonian of the spin chain is the modified Heisenberg−XX model, the perfect transfer of information is only determined by the dynamic evolution of the system itself. That is, the condition of perfect transfer is only determined by the transfer time, and is independent on the length of the chain. On this basis, if a suitable constant magnetic field is applied to the spin chain, the condition to realize quantum information perfect transfer depends not only on the length of the spin chain itself, but also on the magnetic field. Furthermore, the transfer time of quantum information can be controlled by the relationship between the transmission time t, the spin chain length N and the magnetic field B.