The tensile strength of 3-dimension-4-direction braided/epoxy resin composites after accelerated aging for different period of time at 180°C was investigated. The tensile tests of 3-dimension-4-direction braided/epoxy resin composite samples without aging and aged 60 hours, 120 hours, 180 hours, at 180°C were carried out. The damage forms of braided composite samples tested were investigated. The experiment result indicates that the accelerated aging process at 180°C has obvious effect on the tensile strength of braided composite samples. The average tensile strengths of composite samples aged 60 hours, 120 hours, and 180 hours period of time at 180°C are 86.29%, 88.59% and 84.12% of average tensile strength of braided composite samples without aging, respectively. This means that the tensile strength of aged braided composites will be decreased. The damage form of samples tested shows that after aging for a long time at 180°C, the resin is damaged badly and becomes brittle which make the bonding force between fiber and resin decrease. This is the reason of the decrease of tensile strength of composites after accelerated aging at 180°C.