Studying the distribution law of PDC bit bottom hole flow field is an effective method to improve the efficiency of cuttings migration,cool the bit and restrain the formation of mud.Using Fluent software,based on κ-ε bi-equation model and closed N-S turbulence equation,Simplec algorithm was used to analyze the effects of bit speed,drilling fluid ejection speed and the number of nozzles on the bottom hole flow field distribution when the total flow area was the same.The results show that when the bit speed increases from 90 r/min to 110 r/min,the increase of the bit speed has a significant effect on the improvement of bottom hole turbulent kinetic energy and velocity.However,when the rotational speed reaches 120 r/min,the turbulent kinetic energy and velocity of the bottom hole decrease slightly,and increasing the rotational speed of the bit is conducive to cleaning the bit surface from outside to inside.When the ejection velocity of drilling fluid increases from 5 m/s to 9 m/s,the turbulent kinetic energy and velocity of bottom hole increase with the increase of jet ejection velocity.Increasing the ejection velocity of drilling fluid can make the vortex close to the well wall or the bit body,inhibit the increase of the vortex area,and facilitate the migration of cuttings.When the total flow area of the nozzle is the same,the diameter of the outer nozzle is reduced,the number of outer nozzles is increased from 3 to 4,and the turbulent kinetic energy and velocity of the bottom hole are increased,which is conducive to the migration of the bottom hole debris,but leads to the increase of the low-speed area in the center of the bit surface,which is not conducive to the cleaning of the bit surface.