Abstract: In this paper the mechanism of plastic fatigue crack growth（PFCG）was analyzed and an appropriate criterion was proposed. Elastic-plastic （incremental） finite-element method was used to study PFCG. As an example, a central cracked plate with pulse uniaxial tension was used to demostrate the initiation and the processes of the stable crack growth. Experimental data were compared with the computational results. An approximate equation for PFCG was given and the possible ways for engineering use of this equation were pointed out.