The invention discloses a simulation test system and a test method for coal stratum gas dynamic permeability improvement seepage and displacement, which comprise a fluid injection system, a model sealing loading system and a data acquisition, processing and control system. The simulation test system and the test method for coal stratum gas dynamic permeability improvement seepage and displacementcan achieve the function of injecting fluid (gas, steam and liquid) into large-scale coal and rock bodies under different loads, can be used for simulating permeability improvement measures such as coal seam hydraulic fracturing, hydraulic cutting, blasting cracking and the like, can be used for simulating coal seam gas increasing measures such as gas injection, heat injection and the like, can monitor physical quantities such as fluid flow, pressure, solid stress, strain, temperature and the like in the coal and rock bodies in real time, and can find out multi-field coupling evolution rules such as a gas pressure field, a stress field, a deformation, a temperature field and the like in the fluid seepage process under the conditions of pressure bearing and pressure relief. The whole systemhas the advantages of simple structure, clear division of labor and convenient disassembly and assembly, can provide test parameters for permeability improvement and production improvement technologies such as hydraulic fracturing, hydraulic cutting, blasting cracking, gas injection, heat injection and the like, and can provide a verification platform for theoretical research.