HDCS-2 well is a coalbed methane parameter well and production test well deployed in the Nileke Depression of the Ili Basin. Through optimizing drilling fluid parameters， high viscosity drilling fluid flushing， explosive loosening and other technical measures， the drilling complexity problems are solved including block falling， drilling tool obstruction during the tripping， and buried drilling in long open hole of the coal bearing strata， ensuring the completion of the project and the achievement of the geological objectives. Rock mineral analysis testing and scanning electron microscopy observation were conducted using samples from Well HDCS-2， and a three pressure profile was constructed based on logging data to analyze the mechanism of wellbore instability. Improved measures for subsequent projects are suggested as follows： three-section well configuration and a high shear anti collapse drilling fluid system should be adopted， high viscosity drilling fluid （drip） can be configured for well flushing when encounteres falling blocks in the well， slow drilling and tripping， optimizing the drilling tool assembly as well as equip drilling vibration hammer during drilling in coal bearing strata. The study can provide valuable practical guidance for subsequent coalbed methane drilling in the region.