Abstract: Cuttings transport experiment device for extended-reach horizontal well was established based on the similarity system theory. The parameters similarity between the model and the prototype was deduced using the similar particle Reynolds number. Then, research was made on the variation of 10 parameters (i.e. annular velocity, mud density and effective viscosity, cuttings density and size, drillpipe rotation speed and eccentricity, inclination angle, rate of penetration and borehole size) with the dimensionless cutting-bed thickness. On this basis, a steady dimensionless cutting-bed thickness equation for extended-reach horizontal well was established with the nonlinear regression method, and the model was verified through literatures. The model provides a significant guidance for borehole cleaning of minimum cuttings transport flux and the optimization of ROP for extended-reach horizontal wells.