The invention discloses a mud rock sample and a device and a method for remodeling the mud rock sample by rock fragments, and belongs to the technical field of deep oil and gas reservoir drilling and depleted gas reservoir utilization. The mud rock sample is prepared from mud rock drilling fragments. The device comprises a sleeve, a bottom plate, a pressing plate and a force application mechanism. The method includes the steps: acquiring the mud rock seam drilling fragments; grinding the mud rock seam drilling fragments to obtain grinded mud rock seam drilling fragments; adding water into the grinded mud rock seam drilling fragments and stirring the fragments to obtain mud rock seam drilling fragments capable of being pinched and lumped; placing the mud rock seam drilling fragments capable of being pinched and lumped in the device, pressing the fragments and taking out pressed fragments to obtain the mud rock sample. By performing mechanics evaluation of the remodeled mud rock sample, the sealing performance of an abandoned well can be evaluated, and a reference is further provided for whether to perform workover treatment or not.