<p>Continuous circulation technology can realize the continuous circulation of continuous pumping during drilling, which can be used to improve borehole cleanliness in extended-reach drilling and prevent cutting bed accumulation from adversely affecting downhole operations. This paper describes the mechanism of continuous circulation technology and the advantages and disadvantages of its supporting equipment, analyzes the theoretical model of cutting bed migration in extended-reach drilling, studies the distribution, thickness and migration law of cutting bed when continuous circulation technology is used, and optimizes and recommends the flowrate, ROP and drillstring rotation speed of well Panyu A in eastern part of the South China Sea. The results show that the cutting bed of the extended-reach drilling has wavy distribution and dynamic migration with time, and the migration velocity of the cutting bed is inversely proportional to the hole size. The migration direction is from the bottom of the well to the head of the well. The thickness of the cutting bed is the largest at the beginning of the horizontal section, and the thickness near the bottom of the well is the smallest. The research results provide a theoretical reference for borehole cleaning control in extended-reach well.</p>