In this work, failure mechanisms and damage evolution in low-thickness composite laminates are numerically simulated. The effect of thinning ply on the strength and damage evolution of composite laminates is investigated. Micromechanical modeling is performed to study damage initiation and propagation mechanisms and ply thickness or in situ effect in thin-ply carbon fiber-reinforced laminate under transverse tension loading. Two different sets of models are examined. The first set of the thin-ply laminate models contains a representative volume element (RVE) of 90° lamina constrained between two homogenized 0° plies. Thicknesses of models with embedded 90° lamina were 30, 60, 90 and 120 µm. In the second set, two models with 30 and 90 µm of 90° thin ply as the outer layers with embedded homogenized 0° layer are considered. Micromechanical analysis is combined with augmented finite element method to provide high-fidelity results of damage evolution. Random fibers' arrangement and interface toughness and strength normal distribution are considered to capture the composite stochastic behavior. It is shown that the damage initiation and propagation locations are affected by the thickness of 90° lamina and distributions of fracture properties within the RVE.