The comb-like multi-lateral hole is one of the main technical methods for coalbed methane mining. Study of the distribution of cuttings under different conditions in the horizontal hole, which works as the mother hole of comb-like laterals, can be used as an important basis for the selection of drilling parameters. Based on FLUENT fluid dynamics simulation software, the paper analyzes the effects of drill string rpm, drilling fluid viscosity, annulus velocity, debris concentration, debris particle size and borehole eccentricity on the cuttings-carrying capacity in horizontal holes. The result can provide a scientific basis for rational selection of drilling parameters during the drilling process.