This paper investigates the tensile damage process and strength in glass fiber reinforced plastics (GFRP) cross-ply laminates experimentally and numerically. Detailed observations are conducted with a video microscope to comprehend the damage process in the 90 o ply. Experimental results indicate that the strength can be approximately estimated from the strength of the 0 o ply, independent of the thickness of the 90 o ply. Based on these experimental results, we propose a new Monte-Carlo simulation for predicting the damage process and strength in cross-ply laminates. The transverse cracks are expressed by utilizing the cohesive elements, considering both local strength and fracture toughness of the 90 o ply. Consequently, the stress-strain relationship, the crack progress, and some characteristic phenomena, such as the constrained effect and incomplete transverse cracks, observed in the experiments can be expressed with this simulation.