Through measurement of fracture toughness of 2219 aluminum alloy three-point bend specimen and observation of fracture surface and microstructure at different temperature, the influences of temperature and heat treatment status on the fracture toughness of 2219 aluminum alloy are discussed. The results show that temperature has an important influence on the fracture toughness of 2219 aluminum alloy. Compared with fracture toughness in room temperature, the fracture toughness is increased by 36% at low temperature. Heat treatment status also affects fracture toughness greatly, and fracture toughness in the T62 state is better than that in the T87 state. In conclusion, the reason why enhancement of fracture toughness of 2219 aluminum alloy at low temperature appearance is concluded.