Abstract: The horizontal directional drilling technology, introduced into China in the 80's of 20 century, is effectively and widely used in pipeline crossing, and so far nearly a hundred rivers have been successfully crossed. With the construction of large diameter and long distance pipelines, the horizontal directional drilling has a possibility to initiate several serious geological problems, such as sinking, surface settlement and gushing under some special engineering geological and hydrogeological conditions. The article makes overall analyses on the mechanism of these problems.