Disclosed herein is an external airbag deployment method. The method includes setting, by a controller, a detection area located in front. In addition, the method includes setting, by the controller, a target object from objects detected in the detection area, when an object has a relative velocity greater than a first reference, an overlap greater than a second reference, and a TTE less than a third reference, wherein TTE is a remaining time until the object collides with an airbag cushion when the external airbag is predicted to be deployed. Furthermore, the method includes determining, by the controller, whether a relative velocity and an overlap, predicted at a time when the target object is predicted to collide with the vehicle, are greater than predetermined levels and deploying the external airbag when the predicted relative velocity and overlap are greater than the predetermined levels.