In 2011，the “Arab Spring” broke out. Affected by the street movements of Tunisia，Egypt and some other countries，the major cities in Yemen also witnessed an outbreak of anti-government demonstrations，demanding President Saleh，who had been in the ruling for as long as 33 years，step down. Although he used a carrot and stick method to seek to end his presidency by 2013，Saleh had to accept the GCC mediation program by transferring power to Vice President Hadi and exiling in Saudi Arabia in the context of tribal and military rebellion and the pressure from western and Gulf countries. Yemen’s political transition is seen by western countries as an example of peaceful transition and referred to as the “Yemen model”. However，Yemen fails to move towards peace，stability and development since the transition；instead，it has been trapped in a deep crisis after the fragile political balance was broken. Given the current chaotic situation，Yemen as a country is in the brink of collapse，and has become a regional security vortex as well as the stage for the game of great powers.