Abstract: The multiple fracture theory is the hydraulic fracturing frontier theory, especially for the coal, the fractures, physical and mechanical properties of coal are different from homogeneous sandstone. The study of multiple fracture theory is difficult and faces many problems. Based on the basic theory of elastic mechanics, rock mechanics, fracture mechanics and fluid mechanics, and then combining with the multiple fracture theory and bottom hole pressure synergetic theory, after the analysis and calculation of the multiple fracture mode, we thought that overall fluid loss coefficient, flow and principal stress difference all influence the connection probability and extending direction of the multiple fractures in the near wellbore area.