Low-cycle fatigue experiments of tension-compression, torsion and tension-torsion with holding time were performed. The interaction law of creep and fatigue under multiaxial stress at high temperature was investigated, and the micro-mechanism of equilibrium diagrams was analyzed. A united equation of fatigue life under multiaxial stress was proposed. Low-cycle fatigue experiments of tension-compression, torsion and tension-torsion with holding time were performed. The interaction law of creep and fatigue under multiaxial stress at high temperature was investigated, and the micro-mechanism of equilibrium diagrams was analyzed. A united equation of fatigue life under multiaxial stress was proposed.