Abstract: As the geological structure is very complicated, a series of down-hole troublesome conditions have been encountered during the course of drilling operation in block D of Myanmar, for this reason, the drilling operation was in the inefficient state, and the exploration headway was very slow. This article systematically introduction the down-hole troublesome conditions have been encountered in the course of drilling operation in block D of Myanmar, such as serious wellbore collapse, difficult hole inclination control owing to the steep structure, badly drilling fluid lost circulation, limited drilling fluid density safety window and so on. Aiming at the above mentioned down-hole problems, a series of effective measures have been adopted in the course of drilling operation. Thereby the drilling operation in block D of Myanmar was successful, meeting the requirement of exploration and acquiring well oil and gas show.