On the basis of field theory of physics and existent researches, the characteristics of resources extensity are discussed and the concept of resources field are put forward. Like the physical field, the resources field is also an interactional extensity, which possesses the unique characteristics. The theory of resources field presents the characteristic quanta of resources field including resources field difference, resources field forces etc, which can explain the resources flow from the point of view of the force. The essence of resources flow is as follows: the potential difference is the essence of the resources flow and has the direct relationship with its intensity; the resultant force of resources field force and outside forces including motive forces and resistance is the foundation and direct impetus of resources flow. In addition, the quantitative formulas of resources potential difference and resources flow are presented. Using the resources field theory and quantitative formulas, the regional and departmental flows of labor forces resources in two counties (Ningjin Township and Zhangxuewu Township County of Shandong Province) are analyzed and compared.