Various thermal correlations as well as the effect of intrinsic decoherence on the correlations are studied in a two-qubit Heisenberg XY Z spin chain with the Dzyaloshinski-Moriya (DM) interaction along the z direction,i.e.Dz.It is found that tunable parameter Dz may play a constructive role on the concurrence C,classical correlation (CC) and quantum discord (QD) in thermal equilibrium while it plays a destructive role on the correlations in the intrinsic decoherence case.The entanglement and quantum discord exhibit collapse and revival under the phase decoherence.With a proper combination of the system parameters,the correlations can effectively be kept at high steady state values despite the intrinsic decoherence.