Model LQ-100 DTH rigill is a new generation of light-duty product.A greater innovation in the design of main structures of this rig was made. For example, the straight-linked bearing variable drive system and the isolated side air-supply installation were used. The piston-type air motor was firstly used as the rotary power source of DTH rig. The use of thes new tchniques made the whole drill performance enhance greatly, which can be presented enough in the test of this drill.