In the Spring and Autumn Period, the fastest and easiest way to become a monarch, in theory, is to become the country's crown prince. However, history tells us that between the crown prince and the real monarch there lies a great distance. The crown prince does not only have to pay attention to malicious persecutions from their parents, brothers and uncles. They sometimes also need to seek support from domestic nobility and foreign princes. A careless move could threaten their claim to the crown and even their life. This paper intends to explore the key factors in the Spring and Autumn Period that allows a crown prince safely to become a real monarch. These factors would allow us a deeper insight into the important characteristics of this historical period.