The invention provides an SINS / CNS integrated 
navigation system based on comprehensive optimal correction and a navigation method thereof, and belongs to the technical field of integrated navigation. The integrated 
navigation system comprises an astronavigation subsystem, an 
inertia navigation subsystem and an 
information fusion subsystem. The navigation method comprises the following steps: analyzing celestial fix based on 
starlight refraction, building up 
navigation system state equations, building up navigation 
system measuring equations and performing 
information fusion of an integrated navigation 
system based on Kalman filtering. According to the invention, by utilizing the basic principle of 
starlight refraction indirection sensitive 
horizon and a large viewing field 
star sensor, the characteristics of a plurality of 
fixed stars can be observed at the same time, and the 
starlight refraction indirection sensitive 
horizon method is applied to aircrafts that do not fulfill track 
kinetics, so that the problem of high-precision autonomous 
horizon of the 
celestial navigation system is solved. According to the invention, position and posture information of the 
celestial navigation system are fully utilized to perform comprehensive optimal correction on the SINS deviation, so that the integrated navigation accuracy is significantly improved.