The invention relates to a multistage plug classification plugging method suitable for a fissured stratum. The multistage plug classification plugging method includes the steps that first, the averageopening of fissures in the periphery of a well is determined to be D, bridging particles with the particle size being slightly smaller than D are used in first-stage plugging, the average particle size of the bridging particles is denoted as D<1>, the average particle size D<2> of plugging particles used in second-stage plugging is larger than D<1> / 4, and smaller than D<1>, and the particle sizeof each of the following stages of the plugging particles is successively determined through the same method until the average particle size D<n> of the last stage of the plugging particles is small enough to form a dense sealing layer; second, plugging grout only containing the bridging particles with the average particle size being D<1> is first injected through slugs to form a bridging particlelayer; third, plugging grout containing the plugging particles with the average particle size being D<2>-D<n-1> is injected in several times through a plurality of slugs to form a particle filling layer; and fourth, plugging grout with the average particle size of the plugging particles being D<n> is finally injected through the slugs to form the dense sealing layer. According to the multistage plug classification plugging method suitable for the fissured stratum, the principle is reliable, the fissures in the periphery of the well are more effectively sealed, the cost is saved, and the broadapplication prospects are achieved.