Hydraulics analysis is the key of hydraulics design when drilling coiled tube wells. Based on the exiting researches, a method of hydraulics analysis when drilling horizontal slimholes with coiled tube is proposed and some cases are calculated and analyzed. The results show that, bending the coiled tube will increase the pressure loss and the increasing degree will increase with the increase of pump rate. The tube with 50.8 and 60.3 millimeters outside diameter are recommended to drilling coiled tube wells. To control the annular pressure loss, the rate of outside diameter of tube to borehole diameter had better be smaller than 0.5. Eccentricity decreases pressure loss and cuttings bed has the reverse effect. And the influence will be more obvious relevantly as the annular size is smaller and the cuttings bed height is bigger. When drilling a regular well the pump pressure increases with the increase of depth while the pump pressure almost remains stationary or decreases slightly in some case during coiled tube drilling.