Abstract: Hydraulic fracturing is the key technology for efficient development of coalbed methane.The distribution and communication of hydraulic fractures directly affect the fracturing effect. The research progress of true triaxial physical experiment, numerical simulation and field engineering test is systematically combed around the mechanism of hydraulic fracture propagation in coal seams. The effect of geological factors and construction factors on hydraulic fracture propagation is discussed, and the problems and development trends in the study of hydraulic fractures in coal are summarized. The conclusions show that the true triaxial physical simulation test system can simulate the in-situ stress and temperature conditions of the reservoir, and the formed multi-well type specimens can simulate open-hole and directional perforation fracturing, and the acoustic emission, electrical and optical monitoring systems are used to describe the fracture morphology. Secondly, the numerical simulation method for crack propagation has been extended from single finite element method, extended finite element method, boundary element method and discrete element method to continuum-discontinuum element method which combines finite element method and discrete element method. It can simulate crack propagation along any path without remeshing. Thirdly, the field verification method can reflect the fracture propagation morphology under real geological-engineering coupling. While verifying the results of physical experiment and numerical simulation, it reveals the new problems encountered in the application of fracturing technology. Finally, the propagation behavior of hydraulic fractures is affected by the coupling of geological-engineering factors such as in-situ stress, natural weak surface, rock mechanics parameters, displacement, fracturing fluid viscosity, fracturing fluid dosage, and perforation parameters. In order to further explore the propagation law of fractures under ultra-large-scale volume fracturing, the development proposal such as improving the visual true triaxial hydraulic fracturing simulation test system, developing a multi-fusion hydraulic pressure numerical method, and constructing an integrated platform for quantitative analysis of the sensitivity of fracture main controlling factors and intelligent decision-making of fracturing parameters are proposed.Through the comprehensive analysis of the existing literature, the research methods and influencing factors of fracture propagation are summarized in order to provide reference for subsequent research and practice.