Wireless sensor network（WSN） is a new technology recently developed with great potential in large number of fields including earth observation

environmental monitoring

agriculture

resource management

public health

public security

transportation

and military.In this paper

the content and development of WSN technology are first introduced here.It is considered as an expansion of remote sensing and they support each other well.The potential of WSN in earth applications and its general trends are discussed and fundamental questions are raised.It is suggested that WSN should be highly developed in the field of earth observation.A few near-term applications of WSN in environmental monitoring are proposed.