The horizontal directional drilling(HDD) technology has been widely used for laying various pipelines, and has the advantages of high construction speed, small damage to the ground, and no interference to the use of the existing pipelines. However, in collapsible formation such as sand pebbles and fine sand, conventional singletube HDD technology often encounters accidents such as guiding deviation and borehole collapse. Based on the existing technology, a dual rod horizontal directional drilling system has been developed, including the doublerotary drilling rig, the inner and outer drill rods, and the dual rod guiding section. The field application proves that the dual rod system has the advantages of high guiding precision and sensitive adjustment direction, and can overcome the problems of poor guiding precision and borehole collapse caused by collapsible formation.