To reduce the cost of bomb and enhance the equipment efficiency cost ratio, an algorithm research about integrated navigation system for low cost guided aviation bomb. A low cost and high precision combined navigation system is then developed by using extended Kalman filter algorithm, MEMS gyroscope and accelerometer assisted by GPS. UAV flight experimental data is carried out to verify the navigation system, and get the error data. The results are subsequently compared to the stand-alone inertial navigation solution. The experiment results show that the positioning accuracy of this system can reach 2 meters, which can satisfy the requirement of guided aviation bomb flight. In addition, it has engineering practical significance for updating regular conventional bomb.