In order to study the low-cycle fatigue behavior of a new powder superalloy A3, fatigue tests with total strain amplitudes from 0.6% to 1.4% at 700℃ were conducted. Fatigue test results were analyzed including cyclic stress-strain responses, Massing characteristics and strain-life curves. The fatigue life data were fitted by Manson-Coffin equation, Ostergren model and three-parameter energy method. The accuracy of fatigue life prediction obtained by Manson-Coffin equation is optimum. The micro-mechanisms were studied through scanning electron microscopy (SEM). As the strain amplitude gets larger, the number of fatigue sources increases, and the location of the fatigue source changes from the core of the sample to the surface, and the area of the crack propagation decreases while the ductile fracture zone increases. The observation of these three typical areas of fatigue fracture shows that light white river-like lines were found around the fatigue origin in the crack initiation zone which direct to crack propagation. Secondary cracks were found in the crack propagation zone. Dimples and cleavage fracture characteristics were found in the ductile fracture zone. The fatigue fracture mode of A3 alloy is mainly trans-granular.