Abstract: The tension torsion thin walled tube specimens were used as the researching object. On the basis of analyzing the varying characteristics of the stress and strain on the multiaxial critical plane, the maximum shear strain amplitude and normal strain excursion between adjacent turning points of the maximum shear strain on the critical plane were used as two main parameters of controlling the multiaxial fatigue. Two kinds of multiaxial fatigue damage parameters of the tension mode and shear mode are proposed, which do not include any material constant in damage parameters, and may be used under either proportional loading or nonproportional loading. The given multiaxial fatigue damage models by means of the presented damage parameters were used to predict multiaxial fatigue life, and the results are satisfactory by two kinds of material experimental verifications.