A three-dimensional (3D) finite element model is established for the progressive damage analysis (PDA) of the double-stepped-lap joints of adhesive-bonded composite under tensile loading. The laminate is modeled with the constitutive equations of continuum damage mechanics (CDM) in an orthotropic damage. The co-bonding layer is simulated by the cohesive zone model (CZM). Appropriate criterions are chosen to predict the initiation and progression of the damage. The failure modes and bonding efficiency of the double stepped lap joints are predicted. Also, the effects of various parameters, such as step length, overlap length and thickness of the additional plies on the failure modes and bonding efficiency are investigated.