Disclosed are a method and device for controlling top coal caving performance by means of pulse hydraulic fracturing. The device comprises a hydraulic fracturing pump set (7), a high-pressure rubber hose (8), a packer (6) and a high-pressure sealing mounting rod (5). The hydraulic fracturing pump set (7) further comprises a hydraulic fracturing high-pressure pump (7-2) and a hydraulic fracturing pulse pump (7-1). The device and method are capable of combining the advantages of the methods of pulse fracturing and conventional hydraulic fracturing, first generating a fracture network in coal by means of pulse hydraulic fracturing, and then further expanding the fracture network by using conventional high-displacement hydraulic fracturing so as to fully modify the coal structure, thus reducing top coal fragmentation, and improving top coal caving performance. The device and method may enable top coal to generate sufficient fractures to weaken the top coal, thus improving top coal caving performance and reducing the caving fragmentation of the top coal, while being convenient for construction, being safe and reliable, and reducing the waste of resources.