In view of the research deficiencies in the flow field characteristics and rock-breaking and hole-forming mechanism of the multi-hole rotating jet bit for water jet radial drilling in underground coal mines, numerical simulation and indoor experiments were carried out. By using the RNG k-ε turbulence model to simulate and analyze the flow field characteristics of the forward nozzle of the multi-hole rotating jet bit, the results show that at the same bottom hole surface, the jet velocity and pressure gradually decrease with the increase of the spray distance, and the axial velocity of the nozzle jet shows the same attenuation law with the increase of the spray distance. The axial velocity of the 20° and 30° nozzle jets is larger and decays more slowly, while the 50° nozzle jet has a larger radial velocity, and the combined effect achieves axial and radial impact rock-breaking and hole-forming drilling and hole diameter expansion. The velocity and pressure of the forward nozzle jet at different spray distances show a peak distribution, and as the spray distance and nozzle angle increase, the corresponding lateral radius and jet area of the peak point gradually increase. Using the laboratory high-pressure water jet rock-breaking and drilling test system, the dynamic process of rock-breaking and hole-forming and the hole-forming effect were analyzed by using homogeneous sandstone and anisotropic raw coal specimens. The results show that under the rotation effect, the forward nozzles with different angles achieve scanning rock-breaking along their respective tracks, forming inner, middle and outer ring fracture zones, and the sandstone is progressively broken and a hole is formed as the nozzle advances, resulting in a regular circular cross-section hole. Further comparison of the hole-forming effects of the sandstone and raw coal specimens shows that the hole diameters are 24 mm and 38 mm respectively, and the hole-forming effects are good, basically meeting the requirements of water jet radial drilling in underground coal mines, providing a reference basis for the subsequent optimization of the structural parameters of the multi-hole rotating jet bit.