Abstract: The conventional air hammer drilling technology has been developed rapidly and used widely in oil and gas under-balanced drilling,and its successful application provides a wide space for the development and application of pneumatic down-the-hole hammer (DTH).Based on the systematic analysis and summary of the advantages of reverse circulation air hammer used in gas drilling,the design thoughts and development process of SGQ-320 type hollow-through DTH was introduced in detail,including its structure composition and working principle,key structure parameters and parts design,simulation computation of performance parameters,etc.According to the wellbore size to be drilled,in order to meet the demand of impact energy for rock fragmentation,the mass and key structure parameters of piston were determined firstly,and then the structure and performance parameters of SGQ-320 type hollow-through DTH were designed with computer simulation program.By far,the indoor tests of SGQ-320 type hollow-through DTH had been done,and all of the performance parameters met the design demands.The development of SGQ-320 type hollow-through DTH can supply the favorable technical support for enhancing the drilling speed in complex,deep and hard strata by integration of three kinds of drilling techniques: air drilling,percussive-rotary drilling and reverse circulation drilling.