Abstract: Sticking point of sticking accident during well drilling process mostly lies in the place where the drilling string has larger diameter, so the annular is smaller. Especially in the drilling of complex formation, the position with the bit is where the pipe sticking most easily happens. The use of conventional three-cone bit in sloughing formation has some problems. Based on the analysis and improvement for conventional three-cone bits, we mainly achieve the function of anti-stick by changing the nozzle position, increasing the bit open area, and increasing bit rock breaking capacity. According to the application on Well K21-3 and Well K30P, the anticipated objective has been realized. The improved cone bit has good effect on sloughing formation and coalbed formation.