To study the damage to composite material of lowslowand small target caused by laser irradiationa model of threedimensional transient temperature fields of the irradiated surface was investigated by using a finite element methodand numerical simulation was performed on temperature fields of nylon materials irradiated by a laser beam.The distribution of temperature field and ablation field at different time was obtained.The effect of irradiation time on material damage and ablation process was also analyzed.Furthermorethe influence of the beam distribution and spot radius to temperature fields was discussed.