The two-body thermal entanglement and mixture in a three-spin spin chain in thermal equilibrium state are investigated, and the effects of the temperature and magnetic field on the entanglement and mixture are discussed. It is found that, in the ground state, an important class of states, maximally entangled mixed states, can be generated by controlling magnetic field, which provide a new way to generate maximally entangled mixed states and control entanglement. Further, the spin chain in the thermal equilibrium is used as a quantum channel for quantum communication. The effects of temperature and magnetic field on fidelity are discussed. It is shown that the temperature and magnetic field have vast effects on the fidelity. The relation between fidelity and two-body thermal entanglement is given, which shows that more amount of entanglement does not means higher fidelity.