The invention relates to an experimental device for simulating the spreading of a propping agent in a crack, which comprises an artificial crack, the artificial crack comprises two mutually-parallel transparent plates, the upper and lower ends of the two transparent plates are sealed respectively by an edge-coating frame, the left end of each transparent plate is provided with a simulated shaft, the right end of the transparent plate is provided with a liquid outlet pipe, and the transparent plates, the edge-coating frames, the walls of the simulated shafts and the walls of the liquid outlet pipes define a closed space. According to the invention, under the condition of taking different crack widths, crack surface coefficients, sand expansion ratios, fracturing-fluid leak-off levels, friction resistances in cracks and the like into consideration, the experimental device simulates the spreading situation of a propping agent in the artificial crack, therefore, the experimental device accurately simulates the situations of cracks in stratums, and the accuracy is greatly improved.