Since the appearance of the phrase all-attitude navigation, many scholars have tried to explain this phrase, especially, they put forward valuable opinions on the choice of Eular angles when aerocraft is at vertical.

A new method of combined quaternion and Euler angle was proposed to solve the singularity problem of Euler angle velocity equation at large extent attitude movement and all-attitude angles and jumping problems for the limitary of attitude angle using quaternion method in ejection seat performance simulation.

In order to solve the problem,a idea that adding a outer circle to the tri-circled platform system consists of the full-orientation platform is put forward in the book,and mathematics proof of the idea is offered in this paper.