The invention relates to the technical field of oil and gas field exploitation, and provides a pulse horizontal well volume fracturing device and a horizontal well volume fracturing method. The devicecomprises a coiled tubing, a horizontal section of the coiled tubing is sequentially connected with a connector, a motor head assembly, a centralizer, a pulse tool, an ejector, a positioner and a guide shoe, and the pulse tool, the ejector, the positioner and the guide shoe can generate a high-pressure fluid body. The method comprises the following step of (1) drilling down and determining a perforation position. According to the device and the method, the structure is reasonable and compact, the use is facilitated, through the arrangement, the disassembled and assembled can be quickly achieved, the construction cost can be reduced, a pulse fluid body can be generated by the pulse tool, the pulse fluid body can improve the perforation efficiency during volume fracturing through a nozzle,the generation of micro-cracks in a perforation hole eyelet can be increased, the energy increasing in the perforation hole eyelet is realized, cracks is quickly formed on stratum, the construction pressure is reduced, and the device and the method solve the problem that a traditional volume fracturing reforming technology is relatively limited in a method of reforming a target layer section whenformation fracture pressure is high.