In aircraft positioning and navigation, strapdown inertial navigation has always been a commonly used method, and plays an important role in positioning and navigation. However, because strapdown inertial navigation directly uses inertial sensitive devices, the inherent zero drift of the sensitive devices leads to uncertainty in the accuracy of the calculation, which limits its popularization and application in the field of navigation. In order to improve the expanded application of strapdown inertial navigation, this paper aimed to further improve the accuracy and efficiency of aircraft navigation, and designed a practical aircraft strapdown inertial navigation algorithm, which combines attitude information, velocity information, acceleration information, and inertial device information The measured value of position information is used to construct the attitude matrix, velocity matrix, and position matrix with the help of quaternion method, and then the attitude angle and position of the aircraft can be obtained by solving the quaternion kinematic differential equation. The test results show that the algorithm described in this paper can accurately calculate the attitude and position information of aircraft, and provide reference for the designers of aircraft navigation system. It has certain theoretical significance and practical value.