Pedestrian flow has been focused since last decade.It is not only the demand from the development of pedestrian flow theory itself,but also the request of the public security.And it is wanted the theory could reveal the universal law of crowd behavior.Some classical models and the basic results from them were reviewed.Some empirical results from the pedestrian flow in Mecca pilgrimage were introduced.The Vicsek model which can be used to describe the collective behavior successfully was presented briefly,and the concept of view radius was introduced into our model,for the crowd behavior when escaping is similar to the collective behavior.The relations among evacuation time,view radius and number of pedestrian were discussed emphatically.The effect of obstacle on the escaping pedestrian flow was analyzed briefly with the CA model.