Abstract: Ubiquitous positioning shows great potential for wireless applications but confronts lots of fundamentally technical problems. Recent advanced positioning systems and emerging technologies are described,and a novel ubiquitous positioning technology by using the widely available and economically signals of opportunity in urban is proposed. It also include the principles,characteristics,and trends issues in ubiquitous positioning. An initial investigation test was conducted at a typical urban canyon area in Hong Kong.The result shows that the signals of opportunity assisted ubiquitous positioning demonstration prototypes facilitate a variety of wireless and geo-informatics applications.