The invention relates to a UKF (unscented 
Kalman filter) alignment method for an 
inertia / polarized light integrated 
navigation system under a large misalignment angle. According to the method, the state vectors of the initial alignment of the 
inertia / polarized light integrated 
navigation system are selected to build the nonlinear 
error state equation of the 
inertia / polarized light integrated 
navigation system under the large misalignment angle; a solar vector is calculated according to a polarization 
azimuth angle measured by a polarized light sensor, and a polarized light nonlinear measurement equation is established; a speed error measurement equation is established according to the speed output of an 
inertial navigation system; the unified nonlinear measurement equation of the inertia / polarized light integrated navigation 
system is established by using an augmentation technology; the nonlinear equation of the inertia / polarized light integrated navigation 
system is discretized; an unscented 
Kalman filter is designed to estimate the error states such as misalignment angle, speed error, gyroscopic drift and 
accelerometer constant bias of the inertia / polarized light integrated navigation 
system; feedback correction is carried out on the attitude and speed of the inertia / polarized light integrated navigation system, and the initial alignment 
estimation precision and speed of theinertia / polarized light integrated navigation system under the large misalignment angle are improved. The method has the advantages of high precision, high speed and high autonomy.