The present invention belongs to the technical field of ground-source well heat exchange, and provided thereby are a system for supplying heat by means of stratum coal in-place slurrying and a method for supplying power generation heat by means of stratum coal in-place slurrying. The system for supplying heat comprises a stratum coal slurrying device, a mid-deep layer well pipe device and a heat exchange device. The stratum coal slurrying device comprises a water inlet pump (1) and a coal slurry water pump (2) which are respectively connected to an orientating slurry-taking drill bit (3) by means of pipelines. The mid-deep layer well pipe device comprises a vertically buried pipe (4) and a heat preservation inner pipe (5) arranged coaxially with the vertically buried pipe (4) and inserted into the vertically buried pipe (4). The bottom of the heat preservation inner pipe (5) is provided with a micro-hole pipe assembly (6), the micro-hole pipe assembly (6) is internally provided with an electric heater (7), and an annular cavity is formed between the vertically buried pipe (4) and the heat preservation inner pipe (5). A power source line (17) connected to the electric heater (7) is arranged in the annular cavity, and the coal slurry water pump (2) is connected to the annular cavity. The heat exchange device comprises a water outlet pipe (8) inserted into the heat preservation inner pipe (5) and connected to the micro-hole pipe assembly (6). With the described system for supplying heat, underground coal may be directly burned to generate heat energy, and heat energy conversion may be completed, the process being clean and harmless.