Abstract: Eight drivers were selected with age from 35 to 48,Electrocardiograph,Frecord data collecting system and dynamics GPS are utilized to study the drivers' behavior under emergency in the Transportation Communication Trial Field.The mix effect model,which is affected by obstacle distance,driving velocity, driving time,personality,is established to study the inner relationship.The predict model of maximum steering velocity based on heart rate is obtained and obstacle distance,driving velocity have obvious effect on the estimate value of steering velocity.This can offer new method for the drivers' behavior analysis under emergency.