With the continuous development of national economy and the construction technology, a lot of large-span spatial structures with unique form and complex construction are emerging. The health monitoring system that mainly used in bridge structure is applied in large-span spatial structures gradually. Parameter identification and damage alarming are the core technology of health monitoring. In this paper some structural modal parameter identification methods based on ambient excitation are introduced. Finally, for large span structures with characteristics of low-intensive modes, the response data based on large span structures for modal parameter identification method was summed up, and the critical issues for further research in this field are also presented.