Traffic flow is considered as an important basis for the traffic command and decision-making

and various problems still exist in the current traffic flow measurement equipment.Compared to this the passive acoustic technology has the characteristic affected less by the outer factors as a passive measurement.The method for multiple target motion analysis is analysed and explained based on a integrated space-time spectum which is optimized through particle swarm optimization（PSO）of niching algorithn.In the tests compared to the traditional algorithms

the method manifests well for the distinguishion and location of single and multiple objects.It’s shown that the passive acoustic technology has broad application prospects in the field of the traffic flow measurement.