Abstract: Emergency Evacuation Door(EED) is the only exits in a flight test airplane for flight crew evacuation, whether the EED internal mechanism is functional or not directly affects the flight crew evacuation. This paper analyses the motion principle of the EED in a certain type of flight test airplane from two aspects(lock and unlock) based on the characteristics of its mechanism. In addition, virtual prototypes of the mechanism are established with Lms.Virtual.Lab Motion software to simulate and analyze the motion of EED, with and without pressure load respectively. The result shows the mechanism performs well in terms of operation protection during unlocking and locking, The operating force to unlock the protection mechanism in pressurized condition is larger than that in non-pressurized condition. However, once the protection mechanism is unlocked, the pressure load can assist in opening the door, greater pressure load will result in faster response.